Giacomo Bianchi

An Integrated Methodology for the Design of Parallel Kinematic Machines (PKM)

Abstract The paper describes an approach to Parallel Kinematics Machines design integrating tools for machine configuration, synthesis and analysis. An example is shown for a 6 d.o.f. hexapod prototype developed at ITIA-CNR.

Virtual prototyping of parallel mechanisms

Abstract Industrial adoption of parallel kinematic machines (PKMs) may be eased by the availability of methodologies and integrated tools able to analyse in a short time PKMs of any architecture, providing the key data needed to design the machine. The proposed virtual prototyping environment (VPE) meets these requirements, quickly estimating not only the reachable workspace, and the kinetostatic behaviour, but also the actuator effort, internal loads in the mechanical structure and the effects of lumped structural compliances and of manufacturing/assembling errors. A description of the developed VPE-PKM, based on a commercial multi-body package, is given. Its effectiveness is shown by presenting results obtained by ITIA-CNR during the design of a three-degrees-of-freedom (3DOF) translational PKM for light deburring operations, and comparing them with experimental data.

Kinematic Analysis of Parallel Manipulators

A method for the kinematic analysis of parallel manipulators, based on Denavit-Hartenberg formalism, is proposed. This formulation allows to model separately each joint-link train (defined as the consecutive structural elements starting from the origin of the reference frame associated with the base, to the origin of the reference frame of the mobile platform through one of the links). This methodology has the main advantage of determining all the generalized variables characterizing the model (in order to evaluate the mechanical limits of the passive joints, their characteristic parameters), and not only those associated with the active joints. In this way, it is possible to model manufacturing and assembly errors in the mechanical components, kinematics errors in the actuators.

Model and Analysis of a Novel Piezo-Electric Rotational Motor Based on Deformation Wave Precession

The paper describes the functional behavior of a piezo-actuated rotary motor, based on a novel declination of the travelling wave principle, patented in 2015. A structural model is developed by the Finite Elements approach, together with the equations describing the adopted stiction and stepping mechanism. The geometrical locus corresponding the set of equations is described in the space of imposed piezo displacements. The solution indicates the maximum allowable torque and velocity, as a function of the motor design parameters.

A Virtual Components Approach for Energy Consumption Modeling in the Machinery Sector

In recent years, energy consumption issues, boosted by environmental concerns, are becoming of paramount importance in the manufacturing field. In particular, machinery sector has been the theatre of several initiatives and projects aimed at an eco-efficient design and use of the machines. In this context, energy consumption modeling is considered a powerfull tool to foresee and optimize energy efficiency by design. On the other side, while each company has to develop numerical models of the internally designed machine elements, it has to be taken into account that machine productivity, eco-performance and cost are all strongly influenced by the employed commercial components (e.g. motors, sensors, controllers, transmissions, guide ways), that must be also be modeled but it is unrealistic to expect that the machinery builder develops by himself all required models.In this paper, the industrial adoption of simulation tools and methodologies for energy consumption modeling is regarded as an application of the more general “Model Based Product Development” methodology. In particular, the development of “functional component models”, seen as Virtual Components (“VC”) to be assembled in the Virtual Machine, is suggested as the key to foster co-modeling activity involving suppliers. A proper business model is then proposed to guarantee the sustainability of the co-operation scenario.Finally, the strategy concept is illustrated by some examples concerned with machine tool accessories and components.Copyright

An Integrated Methodolgy for Fixture Design in Mesoscale Machining Taking Into Account Cutting Process Dynamics

In this paper an approach for limiting regenerative chatter in meso-milling operations is discussed, based on the optimal selection of work piece dynamic compliance, to be obtained by using stiffness-adjustable work piece holder devices, called “fixels”. In order to investigate the phenomenon, a FEM model of a meso-machine tool has been developed and coupled with the fixels model. Then, the cutting capability enhancement due to the tuned fixels has been evaluated for a significant meso-milling operation with a commercial tool.Copyright