This paper presents a study of the mechanics of deformation of the four-roll pass cold rolling using an elastic-plastic finite element program. This process has been developed at the Anshan Institute of Iron and Steel Technology, People's Republic of China, where a new four-roll pass small section cold rolling mill has been built. The initial finite element analysis has been carried out for the rolling of 8 mm square section bar from 10 mm diameter round stock under dry friction conditions. The results show clearly how the areas of plastic deformation develop during the rolling process. The distributions of the generalized stress and the generalized plastic strain, both on the longitudinal symmetrical plane and on the transverse cross-sections of the workpiece, have been obtained, and the pressure distribution along the arc of contact has been determined. In addition, the roll separation force and the pass elongation of the workpiece predicted by the finite element program have been compared with the corresponding values measured in experiments when rolling 6.5 mm square section bar from 8 mm round material with machine oil lubrication. Good agreement has been obtained.

A simplified finite element (FE) method for modelling the complex three-dimensional deformation inherent in section rolling is presented. This simplified FE technique has been developed by considering a single slice of material of finite thickness passing through the roll gap, to avoid performing a full threedimensional finite element analysis. Only one layer of a finite element mesh (consisting of brick elements) is generated on the slice of the process material taken from the three-dimensional workpiece. The slice of material is considered to be compressed using a pair of grooved dies, which have the same profiles as the rolls. In order to make this simplified pseudo-two-dimensional model more realistic, the speed of compression of the grooved dies is modified according to the vertical component of the peripheral roll velocity within the contact zone. Equations have been developed to approximate the roll separation force. This method is applied to perform a pre-and post-rolling FE analysis for the rolling process of a special section produced at British Steel's Skinningrove Works. The roll pass design and the stability of the rolling process are evaluated according to the results obtained from the FE predictions. Comparisons between FE results and experiment are made where possible.

No abstract

In response to the low level of automation of the tools used for patient transfer in hospitals and the resulting shortage of nursing personnel, this paper studies the characteristics of existing transfer products and related structural features. A transfer machine based on static transfer is proposed, which can achieve patient transfer between a hospital bed and a stretcher truck. In this paper, the overall structure of the transfer machine has been designed in detail, and the structural design and analysis of important transmission components have been carried out. The finite element strength analysis of the main bearing components has been carried out. Finally, the selection of driving components based on their functions has been carried out. This study provides theoretical and technical support for the development of subsequent transfer machines.