A Novel Method for Measuring the Length of Hot Large Forgings Based on Machine Vision System

Large forgings can be applied to manufacture key parts in large equipment used in petrochemical, shipbuilding, aerospace, nuclear industry. At present, the size of hot large forgings is mainly measured by hand-hold calipers or mechanical gauges through contact measurement method. In order to realize non-contact length measurement of hot large forgings, a novel method for measuring the length of hot large forgings based on machine vision system is proposed. Firstly, the light strips are recognized according to the continuous characteristics of the light stripes in the image acquired by the hot forging dimension measurement system based on machine vision. Secondly, using the sub-pixel edge of light strips acquired by the improved sub-pixel edge detection algorithm, the three-dimension (3D) points of each edge of light strips are calculated, respectively. Lastly, the two-dimensional (2D) points projected from the 3D points onto the fitted plane are used for curve fitting, and the edge of hot part corresponding to each light strip edge is calculated according to the curvature of the fitted curves. The distance between the start point and the edge point on each light strip edge is considered as the length of hot forging at the corresponding edge of each light strip. The length measurement experiment shows that the method can be used to calculate the length of hot large forgings. The measurement error of the length measurement system when measuring part at room temperature is 0.547%. The time for measuring the length of hot forging is 6.8s.

Changing from a Vertical Burr to a Horizontal Burr in the Vertical-Type High-Speed Twin-Roll Caster

Strip casting using a side dam plate produces a vertical burr at the strip edge. In the present study, changing this vertical burr into a horizontal burr using a burr changer is proposed. The burr changer was placed inside the side dam plate. The burr changer was made from mild steel and an insulator sheet and cut along the shape of the roll. The burr changer was placed so as to prevent exhaustion of semisolid metal between the side dam plate and the roll-side surface. When the position of the burr changer was appropriate, the vertical burr changed into a horizontal burr. The horizontal burr was flat. The width of the horizontal burr was affected by the lowest position of the burr changer and became narrower as the lowest position of the burr changer approached the roll gap position.

NUMERICAL ANALYSIS OF EDGE OVER COATING AND BAFFLE EFFECT ON HOT-DIP GALVANIZING

In hot-dip galvanizing process, air jet wiping control is so crucial to determine the coating thickness and uniformity of the zinc layer on the steel strip. A numerical simulation of gas-jet wiping in hot-dip galvanizing was conducted to minimize the occurrence of edge over coating (EOC). The causes of EOC were identified by contrasting and analyzing the airflow fields on the strip edge with and without a baffle. The factors influencing the airflow field on the strip edge during the change in the gap between the baffle and the strip edge were also analyzed. The effect of the distance between the air knife and the strip was evaluated. Technological parameters with on-site guidance role were obtained by combining them with the actual production to elucidate the role of the baffle in restraining the occurrence of EOC. The uniform distribution of pressure and coating thickness on the strip is achieved when the distance of the baffle from the strip edge is about 0.3 times of the jetting distance.

Production Methods of Thin, Narrow and Profiled Steel Strips

This paper is a synthetic presentation of the current state of knowledge on the fundamentals of cold production of thin and narrow steel strips. Such strips are semi-finished products used to manufacture final products which are widely used in a number of industries. The production devices are characterised and methods as well as technologies of their manufacture are discussed. For cases where wire is flattened to obtain strips with naturally rounded edges, the deformation phases with a uniform and non-uniform draft across the width of the strip have been identified. Changes in the widening coefficient and the rounding radius of the strip edge are described for these phases as a function of draft.