Controlling the dynamic characteristics of machining systems through consciously designed joint interfaces

Abstract: The precision of machining systems is ever increasing in order to keep up with components’ accuracy requirements. At the same time product variants areincreasing and order quantities are decreasing, which introduces high demands on the capability of machining systems. The machining system is an interaction between the machine tool structure, the process and the control system and is defined in terms of capability by the positional, static, dynamic and thermal accuracy. So far, the control of the machining system, in terms of static and dynamic stability is process based which is often translated into sub-optimum process parameters and therefore low productivity.This thesis proposes a new approach for control of the machining systemwhich is based on the capability to control the structural properties of themachine tool and as a result, controlling the outcome of the machining process.The control of the structural properties is realized by carefully designed Joint Interface Modules (JIMS). These modules allow for control of the stiffness and damping of the structure, as a result of tuning the contact conditions on the interface of the JIM; this is performed by control of the pre-load on the interface,by treatment of the interface with damping enhancing materials, or both. The thesis consists of a presentation of the motivation behind this work, the theoretical basis on which the proposed concept is based and a part describing the experimental investigations carried out. Two prototype JIMs, one for a milling process and one for a turning process were used in the experimental investigations that constitute the case studies for examining the validity of the proposed concept and demonstrating its applicability in a real production environment.