The Effects of Electric Field Dynamics on the Quality of Large-Area Nanofibrous Layers

This paper presents technological modifications of an electrostatic spinning device, which significantly increase the thickness homogeneity (i.e., quality) of produced layers by creating auxiliary dynamic electric fields in the vicinity of the spinning and collector electrodes. A moving body was installed above the needleless spinning electrode, which destabilized the standing wave occurring on the free surface of the spinning solution. Furthermore, an endless belt design was used for the collector electrode instead of a roll-to-roll design, which made it possible to substantially increase the surface speed of the substrate and, therefore, the dynamics of the electric field at the place of collection of the fibers being spun. As a result, the coefficient of variation of the area weight of 912 samples cut out from the deposited nanofibrous layer, which was (1000 × 500) mm2 in size and had an average area weight of (17.2 ± 0.8) g/m2, was less than 4.5%. These results were obtained only when the dynamics of both the spinning and collector electrodes were increased at the same time. These modifications resulted in a significant increase in the quality of deposited nanofibrous layers up to the standard required for their use in pharmaceutical applications.

A New Cross Wedge Rolling Process for Producing Rail Axles

Rail axles are large-size parts produced in large batches. Currently, these parts are produced by metal forming techniques such as rotary forging, open die forging with hydraulic presses and open die hammer forging (minimum ram weight: 3 Mg). Nevertheless, not only are the above methods far from being efficient, they also lack accuracy (open die forging). As a result, new techniques for producing rail axles are constantly developed. One of such alternative techniques is based on the use of cross wedge rolling (CWR), which is the subject of the present study. An innovative roll design for producing rail axles by CWR is proposed. The rolls are provided with three pairs of wedge tools that act simultaneously on the workpiece and form the part in one revolution of the rolls, i.e., during 20 s. The numerical modelling of a CWR process with the proposed roll design reveals that the solution can be used to produce railway axles with the desired geometry. This technique, however, requires relatively high loads and torques. To decrease the force parameters, the forming process was modified and ran in two operations. The first operation consists in forming the central step of the workpiece while the other one involves the formation of steps on the ends of the workpiece. The results of the new simulation show a significant decrease in the loads and torques, which is caused, among others, by reducing the nominal diameter of the rolls from 1600 mm to 1200 mm. The numerical findings can be used to design a rolling mill for producing rail axles.

Modelling Central Consolidation during Hot Rolling of Cast Products

Extending the range of finished product sizes from a given ingot or concast bloom or billet section is often limited by the minimum area reduction required to ensure effective central consolidation and final mechanical properties. Predicting effective consolidation or level of remnant porosity for a range of steel grade, billet size, pass schedule/roll design and thermo-mechanical conditions has always been an important issue on plant, much more lately in view of recent trends for larger ingots and development of combined forging/rolling strategies. This paper will focus primarily on a fast analytical technique based on roll gap shape and consolidation factors obtained from Finite Element (FEM) Models. New developments based on FEM submodelling are presented briefly. Healing capabilities based on diffusion bonding can be obtained from [1-3].

A Review and Technology Analysis of Rolling Channel Sections in Rolling Mills in the CIS

Requirements for the quality of finished products is continuously increasing. It adducts to improve existing and develop of new schemes roll design. This paper contains the analysis of technological schemes for rolling channels, which are used in the CIS countries. Were described different ways of rolling channels and design features roughing and finishing passes. The authors were compared schemes of UPN-shaped profiles’ rolling on different Iron and Steel Works. The article describes methods for improving the roll design, proposed and implemented by domestic developers. These methods are based on the gained experiences of flange profiles’ rolling and developments of the modern world. It makes possible to reduce manufacturing costs and improve product quality of the channels.

Automating the Design of Cold Roll Forming Roll Sets

The design of cold roll forming roll tools, roll geometry and the number of tool sets, can typically be referred to as experiential design. Within a multi-occupant design office there will normally, for the same sectional profile, be as many different designs as there are designers. This variation in design results in a lack of design consistency and hence makes the process of developing design understanding, increasing profile complexity, maintaining quality, and roll tool predictability very difficult. This paper contains an explanation of the approach taken within the Hadley Group to identify the discrete steps associated with roll tool set design. To implement methods to standardise these steps including strip width and clearance calculations. With appropriate design steps standardised an explanation is provided as to how elements of this design process is automated leading to a system of assisted design for roll tool sets. The results, including increased design capacity, of the assisted roll design after being incorporated into the design office are discussed.