Coupled thermal/structural contact analyses of shrink-fit tool holder

Abstract

Design of shrink-fit tool holders requires fast reliable stress analysis (from operational point of view). However, such an analysis exhibits difficulties due to its nonlinear nature. This article shows how to execute a complete cycle of design analysis iteration utilizing finite element analysis approach. Each finite element analysis cycle of iteration requires both transient thermal and structural coupled analyses. For a particular initial design, the transient heating of shrink-fit holder is first simulated, that is, the tool inner diameter hole expands due to inductive heating from its nominal value, so that cutting tool is easily inserted. Following this, both tool holder and cutting tool are allowed to cool down so that shrink-fit design forms a uniform contact pressure distribution. Finally, cutting tool is fixed at the contact interface. Then, the tool assembly is rotated (for testing) up to a cutting speed of 40,000 r/min, where transmission torque is also calculated to assess design limits for safe/efficient torque transmission. All of these analyses complete a single design cycle of iteration of the shrink-fit tool holder. Results presented include the calculation of change in shrink-fit pressure values over preload and preload + spin cases. Further assessment is also made to make sure overall elastic equivalent stresses at maximum operating speed are below yield limit of the tool holder material used in the design.