This paper is concerned with chatter in tandem cold rolling mills, which has been recognised to have close relation with friction conditions in roll bites. However, the relation between rolling conditions and the stability of vibration has not been clearly understood. Therefore, an attempt is made to understand how the rolling conditions can be related with vibration phenomena, through numerical simulations.Firstly, a theoretical model is constituted to simulate the vibrational behaviour of a five-stand continuous rolling mill, and the stability of the mill vibration is evaluated, introducing a disturbance to the static rolling conditions. The results of the calculation show that the vibration is greatly influenced by rolling speed and friction coefficient. With increase in rolling speed, the mill vibration tends to be self-excited. Also, the results show that optimal range of friction coefficient exists in which the vibration is damped and the mill is stable against the disturbance.Secondly, a simple self-exited vibration model is proposed and the stability index is proposed for further understanding of the phenomena. An analytical approach is made to predict the stability of the rolling process. With this model, it is shown that the rolling force and the delay of the response to the change in gap have a major effect on self-exited vibration. Also, the calculated optimal range of friction coefficient in the continuous rolling simulation can be explained by using the analytical model.

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Arrayed atomic force microscope (AFM) cantilevers for parallel scanning probe lithography (SPL) have been fabricated by silicon micromachining. Fabrication is based on three KOH etching steps and local oxidation processes. The curvature radius of the tips is as sharp as 20 nm. A laser beam focused onto the middle probe enables us to observe the wafer for alignment and confirm the patterns after the SPL operation. Parallel SPL on N-octadecyltrimethoxysilane (ODS) self-assembled monolayer (SAM) films is susessfully demonstrated with five probes. Good alignment and homogeneity are obtained with simple operation. Parallel SPL for parallel quantum device fabrications is also reported.

Synopsis : O/W emulsions are widely used in tandem cold rolling mills as coolants, in order to reduce friction forces and prevent heat scratches. The lubricating properties may be determined by various factors, and the amount of plated out oil on strip surface is one of the important ones, as well as dynamic concentration mechanics of emulsions at inlet of roll bite, on which much interest has been paid since 1970s. However, plate-out oil film formation has been recognized as a quite important factor in production mill operation, and the understandings of more details are necessary for higher speed and more efficient cold rolling mills. Therefore, the paper is concerned with the plate-out properties, especially the oil film formation in a quite short time. Because the plate-out oil formation is caused through phase transformation of O/W emulsion to oil film, the process may be time dependent, even if the time is quite limited in production high-speed rolling mills. In this paper, firstly a new method to evaluate the amount of plate-out oil is proposed, which makes it possible that the evaluation in quite a short time less than 0.1 s. Then, the time dependency of the oil film formation is clarified, and the amount of plated-out oil increases with time from emulsion supply to strip surface. Also, the influence of oil concentration, oil droplet size of O/W emulsions and other factors are examined by the method, which are compared with the results by conventional test methods.

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