To secure the precision forming capability of a press while reducing its production and transport costs, the development of stiff and lightweight frame is important. In this study, the topology and multi-objective structural optimization problem of a frame structure was introduced with an effort to develop highly stiff and lightweight frame for a mechanical press with 300 ton capacity. First, a design space model was constructed to derive a new frame structure different from the existing one for topology optimization. Using the design of experiments and the structural analysis model of the frame structure improved based on the topology optimization result, the multi-objective optimization problem was established with loop stiffness and mass of frame as objectives and the steel plate thickness as design variable. The review on Pareto optimum solutions of the multi-objective optimization problem revealed the fact that this optimization method could significantly contribute to the high stiffness and lightweight frame structure for a mechanical press.

We report a centerless grinding machine which can perform multi-function with 600 mm wide grinding wheels. By increasing manufacturing area, long workpiece such as camshaft and steering shaft, is allowed to grind more quickly, compared with cylindrical grinding system. In this paper, the design of centerless grinding machine puts emphasis on symmetry to exploit the thermal stability. Results of finite element analysis shows that the difference of the structural deflection in the front and rear guideways is less than 1.5 μm due to symmetric design. The difference is less than 3.0 μm, even though the thermal deformation is considered. According to the performance evaluation, the radial error motion of the G/W spindle, which is measured by applying Donaldson Ball Reversal, is about 1.1 μm. The yaw error of the G/W slide is improved from 2.1 arcsec to 0.5 arcsec by readjusting the slide preload and ball screw.

A high-precision centerless grinding machine has been recognized as a core equipment performing the finish outer-diameter grinding process of ferrules which are widely used as fiber optic connectors. In this study, in order to realize the high-precision centerless grinding machine, the structural characteristic analysis and evaluation are carried out on the virtual prototype consisted of the steel bed, hydrostatic GW and RW spindle systems, hydrostatic RW feed mechanism, RW swivel mechanism, and on-machine GW and RW dressers. The loop stiffnesses of centerless grinding machine are estimated based on the relative deformations between GW and RW caused by the grinding forces. And the simulated results illustrate that the concrete-filled bed has the considerable effect on the improvement of the structural stiffness of centerless grinding machine.