Journal of Mechanical Working Technology最新文献

Surface finishing induces damage such as plastic deformation, residual stresses, and cracking near the finished surface. This damage is characterized by measurement of the residual stress distribution and calculation of crack sizes. A single point indentation model for the evolution of surface damage is described. Finally, processes for controlling finishing induced surface damage are outlined.

This paper reports the results of an experimental investigation into the dependence of the tube-shape and -dimensions on the variation of mandrel velocity and on the values of the tension and the back-tension in the rolling of aluminium tubes in a laboratory two-high rolling mill. The causes of wall-thickness and diameter variations in the rolled tube are identified and the possibilities of controlling the cross-section of the tube are explored.

This paper presents the analysis of a 6 DOF robot end-effector built to study telerobotic assembly of NASA hardwares in space. Since the end-effector is required to perform high precision motion in a limited workspace, closed-kinematic chain mechanism is chosen for its design. A closed-form solution is obtained for the inverse kinematic problem and an iterative procedure employing Newton-Raphson method is proposed to solve the forward kinematic problem. A study of the end-effector workspace results in a general procedure for the workspace determination based on the link constraints. Computer simulation results are presented.

In this study we propose a plasma spraying technique which is combined with the continuous hot rolling method to realize not only an inexpensive but also a high productivity manufacturing process of steel plates coated with high grade materials (among them are cermets and ceramics) and having good adhesion between the coating and the steel substrate. This study also aims at investigationg the best suited combination of working parameters to demonstrate the feasibility of this process.

More specifically, coated steel plates with two kinds of coating materials are made with this technique; first WC-Co coating (a cermet coating) is tried aiming at good wear resistance and then a Y₂O₃ stabilized ZrO₂ coating ( a ceramic coating ) having Ni-Cr alloy as an undercoat is tried to realize a thermal barrier means and/or an anti-corrosive means at high temperatures. Then several factors governing this technique, i.e., coating thickness, rolling reduction rate and heating temperature ( for hot rolling ) are investigated in order to manufacture the coated steel plate having sound cermet or ceramic top surface.

The results are that it is possible to manufacture coated steel plates having a better adhesive strength between the coating and the substrate as compared with an as-sprayed coating by selecting a coating thickness of 100–160 μm, a rolling reduction rate of below 3% and a heating temperature of 600°C in the case of WC-Co coating and 1100°C in the case of ZrO₂ coating respectively.

The Authors propose a new approach in order to evaluate the temperature distribution within the tool in metal cutting. The method, based on experimental tests, carried out by the constant melting point powders technique, and on a finite element analysis of the process, has allowed determining which fraction of the total heat involved in the operation flows into the tool. Consequently the temperature distribution within the whole volume of the tool has been determined for various cutting conditions.

This paper discusses the development of an expert system based on axis orientation of the parts in a three dimensional system. For any part fed to a machine cell, the material handling planning system presents the part to the assembly robot in the desired orientation. Group Technology classification and coding method is used for part identification, as well as for the feeding mechanism design.

The forming of large aluminum panels to attain airfoil sections and complex curvatures for use in modern metal aircraft and aerospace structures poses many problems that are not easily resolved by conventional mechanical forming methods. Textron Aerostructures has developed a forming method that has proven to be highly viable for forming large aluminum panels. This method is called autoclave age forming. The method uses the heat and pressure capabilities of an autoclave along with special tooling and techniques to enhance and exploit the basic stress relaxation phenomenon that occurs during the artificial aging of metal. This paper begins by describing the concept behind the autoclave age forming method. It continues by comparing the forming mechanisms used and the residual stress levels imparted by age forming and cold mechanical forming methods. Then, it will review the enhancements made to age forming by the use of an autoclave and special tooling. Finally, the paper will conclude by presenting production applications of the autoclave age forming method.