Producing Hollow Shafts in a New Horizontal Mill by Novel Flat-Knifing Cross-Wedge Rolling With Single Guide

To meet the requirement of lightweight, there are increasing solid shafts being designed to be hollow in transportation industry. In this study, a novel method of flat-knifing cross-wedge rolling (FCWR) with single guide is proposed including a modified roller, a horizontal mill and a single-guide structure, and its key problems are studied by numerical simulations and experimental tests. A mathematical model of FCWR roller is established, which reveals the wedge length of rollers is effectively reduced by modifying knifing wedge from normalized roller. Further, a horizontal multifunctional mill is invented and constructed to carry out the FCWR experiment with single guide. According to the results from the numerical simulations and corresponding experiments, it is observed that the typical defects of hole expansion and knifing groove are absolutely avoided because the improved flat-knifing wedge produces a radial force to shrink the inner hole and avoid the deformation concentration of the outer surface during knifing stage. Moreover, the single guide rolling performed in the horizontal mill efficiently improve rolling stability because the workpiece is restricted into a smaller workspace. To the authors’ knowledge, all these integrated improvements of FCWR roller, single guide rolling and horizontal mill are innovative, which are of great engineering significance to manufacture hollow shafts on account of the advantages of avoiding forming defect, reducing roller diameter, improving rolling stability and simplifying mill structure.

CALCULATION OF VALUE OF OVERALL EQUIPMENT EFFECTIVENESS AS A BASIS OF PRODUCTIVITY IMPROVEMENT PROCESS SHEARING LEAF SPRING IN PT INDOSPRING TBK GRESIK

PT. Indospring, Tbk as a motor vehicle producer industry is demanded to continuously improve the quality of products made in order to remain competitive in the current era of globalization. This is in line with the amount of demand that shows an upward trend. However, the performance of one of the production equipment that is not running optimally causes the output of production is low. From this problem, how is the OEE measurement as the basis of the proposed improvement design to improve the performance of the production equipment so as to achieve World Class Value standard.In performing these performance improvements, it is used OEE method application, Fishbone Diagram, Pareto Diagram in solving the problems that occur. OEE calculation results show that the equipment in the Eye Forming Process has the lowest OEE value compared to Cutting and Process Punching that is equal to 77.94%. This is due to 2 factors namely Performance Factor (83.83%) and Quality Factor (96.18%). The result of analysis that the biggest factor of Performance (Unplanned Down Time) is the first because the process of set up is 733 minutes (52,47%) and secondly because the problem of mandril jam is 450 minutes (32,21%) and Eye Forming Defect ), The first is Eye forming Deformed 1034 pcs (60.50%) and the second is Eye forming Defect Grip as much as 381 pcs (22.29%). Based on the results of the analysis then made an improvement proposal based on the priority of critical problems that occur to improve the performance of equipment in the process.

Electron Transport in Partially Filled Iron Carbon Nanotubes

We report electron transport properties of iron filled multiwalled carbon nanotubes (MWCNT) with outer diameters of 30 to 80 nm and lengths of 1 to 10 μm. Our study is combined with a structural investigation of the iron core using transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). It was found that high current densities of 1.8x107 A/cm2 increase the conductivity of the MWCNT by a factor of two at 300 K, while the Fe core disappears probably forming defect states in the carbon shells. The enhanced diffusion of iron is most probably the result of local heating of the iron followed by implantation of iron atoms in the nanotube layers.

A Study into Spin-Forming Process of Internal Spline

Spin-forming is a new technique for manufacturing the rotationally symmetric component with internal teeth, such as internal spline and gear. In order to optimize the spin-forming process and improve the forming quality of internal spline, the critical issue, the effect of spin-forming process on product formation was investigated by processing experiments and finite element analysis. The result indicates that it is the flow pattern of metal and friction force in the spin-forming that causes forming defect of product; two pass spin-forming helps to improve the homogeneity of deformation for metal with good plasticity; for internal spline forming, a stepped process is a better spin-forming process compared to a non-stepped one.

Optimization of Forming Technique during Necking Extrusion of Drill Pipe Joints

By using finite element method, the causes of forming defects such as shortage of material and punching recess thickened during drill pipe joints forging were studied and some solutions were put forward. According to the numerical simulation results, one forming defect named shortage of material caused by the metal irregular flow at the bottom of necking die, which can be resolved by reducing the die forming-angle and increasing the width of the punch. On the condition with D0/d0≤2.6 (D0 refers to outer diameter, d0 refers to inner diameter), necking process can be completed with one-step backward extrusion. The thicker punching recess is formed by the accumulated metal which was scraped by the punch during necking extrusion. This kind of defect can not be eliminated, but can be minimized by improving friction conditions.