Design of an Ultra-Light Portable Machine Tool

Abstract

Designing machine tools for in situ machining is a challenging task due to their unique structures and restrictive functional requirements. Such a machine tool should be characterized by low mass, adequate machining accuracy and high machining stability. The paper presents the design of an ultra-light, axisymmetric, portable machine tool for in situ flange face milling. Due to a high compliance of the designed machine tool and a need of maintaining its low mass, structural modification aimed at stability increase were highly limited. Therefore, it was decided to select the spindle ensuring machining stability. The selection of the spindle was supported by finite element analysis. Based on numerical analyzes results a prototype with a proper spindle was build. Then, the accuracy of the finite element model and the predicted stability were experimentally verified, showing a good agreement with the real counterpart. Finally, two general conclusions were formulated: (i) in the case of machine tools characterized by high compliance and limited possibility of modifying their design a good choice may be the selection of a spindle that allows to obtain parameters that ensure stable machining, and (ii) it is possible to build low-dimensional, reliable finite element model without using substructuring or reduction methods, and a well-thought-out discretization and replacement elements of complex load bearing systems instead.

Keywords

• Dynamic stiffness
• finite element modeling
• flange facer
• in situ machining
• onsite machining
• portable machine tools