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Machining and Monitoring Strategies Part 3

Tham khảo tài liệu 'machining and monitoring strategies part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Machining and Monitoring Strategies 451 9.3 HSM - with Non-Orthogonal Machine Tools and Robots Variax Hexapod - Design Concept Non-orthogonal machine tools such as the one simulated designed and developed for HSM applications is typically illustrated in various ways in Figs. 223 to 225 utilising virtual six axes kinematics i.e. namely X- Y- Z- A- B- and C-axes therefore these axes operate without having any true slideways. This particular kinematic concept has actuators that cross each other forming X s instead of meeting at apexes to form triangles as they occur in aircraft flight simulators which uses conceptually similar mechanisms - known as Stewart platforms these configurations being a form of parallel kinematic link mechanism Fig. 223 . To develop this new concept for a machine tool the manufacturer utilised computer-aided technology which played a pivotal role in creating the structural design Fig. 223 . In particular the application of a totally three-dimensional design environment was employed utilising both finite element analysis FEA in conjunction with kinematic analyses. However the Variax design uses a range of uncomplicated or standard mechanical components in its design. While new forms of motion actuators were discarded in favour of conventional and well-proven ballscrew technology with its accompanying motor and drive machinery. Even the gimbals that secure the legs at the base and the spindle carrier are relatively simple devices. With the design of such a high thrust machine a significant problem to overcome was the connection of the spindle to the six legs Fig. 223a . The answer to the connection problem was a simple space frame design allowing all the forces to be either in tension or compression along the structural elements - similar to a bridge design. If one compared this Variax design with that of a plate-type design to secure the spindle to the legs then the former space frame concept improves the mass-to-stiffness ratio by 275 . While