Small elements used in the meshing portion of metal zippers are formed by successive plastic deformations, i.e.,shearing of a preformed copper alloy wire, forging of a sheared piece, and bending of a forged piece, in a chain machine. These plastic deformations are carried out repeatedly and continuously at high speed to form a fastener chain. However, in a new design of zipper elements, owing to the difficulties in forming the designed structures by the deformation process, design and production must be repeated many times to reach an optimal solution. The purpose of this study is to clarify the shearing mechanism of round wire using a simple shape for the zipper element. As result, the shearing process was estimated as follows. In the first step, shearing is proceeded by a shearing force generated by a punch force. During the process, the cut material is compressed, and the height of contact with the punch increases owing to compressive deformation. In the final step, bending stress at the edge of the cutting line reaches the tensile strength of the material and divided from the wire. Then dimples are formed on the cut surface.

A method of using backward extrusion of a cylindrical cup to evaluate the anti-galling ability of a zinc phosphate coating is proposed. In this method, galling generation on the inner surface of the cup is judged by the rapid increase in the extrusion load in the extrusion load-stroke diagram. By using a divided punch, the tip of the punch is left at the extrusion end when the main body of the punch is returned after extrusion, thus the galling situation on the inner surface of the cup is perfectly maintained. It is confirmed that the rapid increase in the extrusion load is caused by the generation of galling, and the residual coating thickness measured by FE-AES at the galling generation stroke is smaller than the protruded peak height Rpk of the punch tip.

Skin-pass rolling (or temper rolling) is the final forming step in the production of cold-rolled steel strips. In operation, the delivery angle is applied to improve flatness and to measure tension, but the resulting strip warping (or bowing) remains. In this study, a series of skin-pass rolling experiments and FEM simulations of its condition are conducted to clarify the phenomena and mechanism of the warping. Certain effects of rolling force and delivery tension can be seen on the level of warping in the experiment. Larger delivery angle leads to larger warping, but the value of warping is saturated up to 6° under the conditions of this study. The strip closest to the delivery point is bent with a given delivery angle, but does not fit the deformed work roll surface. This bending leads to a difference in delivery tension and thus to longitudinal plastic strain at the upper and lower surfaces, causing strip warping.

Roll bending is a useful technology for manufacturing a wide variety of products in small quantities. However, the roll bending of structural channels, which have a complicated cross-sectional shape, causes irregular deformation. On the other hand, there are fewer reports on the bending of structural channels than those on the roll bending of sheet metals. The purpose of this study is to clarify the fundamental forming property in the roll bending of structural channels. In the present paper, we report the results of a finite element analysis of the effects of the processing conditions, that is, the driving-roller groove shape and the distance between the side rollers, on the deformation behavior in the three-roll bending of structural channels.