International Journal of Machine Tool Design and Research最新文献

A compensatory control system for a moderately accurate cylindrical grinding machine was simulated to investigate the amount of possible improvement of the workpiece roundness for a plunge cylindrical chuck grinding operation. Parametric transfer functions of the drive system of the compensatory controller and of form accuracy were identified by employing an autoregressive moving average vector modeling methodology. It has been shown that the workpiece roundness can be improved up to 90 per cent by compensating the work spindle radial error motion at the grinding position.

After a short survey of quick-stop devices in general, the paper describes the design, testing and commissioning of a quick-stop device for use in metal cutting hole manufacturing processes. The device's performance at a theoretical cutting speed of 305 m min⁻¹ (1000 ft min⁻¹) compares favourably with other quick-stop devices. When the quick-stop is actuated at a typical speed and feed the separation distance is 2.2% of the feed rate. Although the device is specifically designed for deep drilling it can be used with other metal cutting hole manufacturing processes.

The investigation deals with a preform design problem in an axisymmetric disk forging where it is required to produce a uniformly deformed flat disk under the presence of friction at the die-workpiece interface. The backward tracing scheme by the finite element method was applied with criteria for controlling the boundary conditions during the process. Three design approaches were presented, and the suggested final design was evaluated by performing simulation. It was concluded that satisfactory results can be achieved by the use of the backward tracing method.

This paper reports the experimental investigations on reducing burr formation while drilling through-holes in metals. Experiments have been planned based on response surface methodology (RSM) technique. Mathematical models correlating response parameters (burr sizes) to the process parameters, e.g. feed, hole size and workpiece hardness have been obtained. Optimal process conditions to minimize the sizes of burr at the entry and exit of holes have been identified. In addition an attachment has been designed and developed to provide continuous modification of feed during drilling. It is reported that the optimal process conditions and the use of attachment can cause significant reductions in the sizes of burr.

This paper shows how the cost of an existing foundation for a large machine can be minimized by optimizing the parameters which define its shape whilst maintaining the required stiffness. The parameters considered include the thickness of the concrete in the machine pit and the platform, the cross-sectional area and the amount of reinforcement in the piles, the number of piles and the spacing between them. The foundation is optimized using two- and three-dimensional models. Both these models have been optimized for different loading conditions and varying stiffnesses.

A non-linear unconstrained optimization technique combined with the finite element method has been used to obtain the optimal designs.

Experiments have been carried out on lead and copper cylindrical billets using simple extrusion forging dies under quasi-static and dynamic conditions to produce boss and flange type components. It was observed that during the initial stages of the deformation process, the flow pattern of the metal is significantly different to what is normally assumed in theoretically analysing the process. The profile of the flange becomes very much tapered and the height of the boss obtainable is dependent on the boss to billet dimensional ratio.

A theoretical analysis is presented based on rigid-plastic property of the billet material which enabled prediction of the tapered deformation profile of the flange under frictionless conditions. The agreement between the theoretically predicted deformation modes and those observed experimentally is found to be very close.