AN IMPACT OF THE STEEL-CONCRETE COMPOSITE SUPPORTING STRUCTURE ON THE DYNAMIC PARAMETERS OF THE MACHINING CENTER

A self-excited vibration, called “chatter”, is a main limiting factor in chip-forming metal machining. The reduction of machining productivity, worsened machined surface quality and the reduction of lifetime of the machine tool parts, particularly the cutting tool itself, occur as a result of the chatter. There are more ways to suppress this undesired effect of machining. The most common and simplest variant is the structural modification of the supporting parts of the machine in order to increase the dynamic stiffness and damping. In most cases, manufacturers of the machining centers use traditional metallic materials (steel, cast iron) for construction of the machine supporting system. However, these materials have some limitations. In order to improve the dynamic parameters of the machine during machining process it is appropriate to combine these materials with others to create hybrid, composite structures. Authors of this article have performed the real experiment in order to test the real dynamic properties of the vertical multitasking machining center with the turning operation prevailing. The individual segments of the supporting structure are made of the composite material – a combination of a steel welded structure filled with high-strength cement concrete.