Materials Science Forum Vols. 697-698

Abstract: A new setup for polishing of diamond films on a high speed rotating stainless plate has been developed, and a rare earth metal plate was used to clear the carbon atoms diffused into the polishing plate. The surface morphology and clearance mechanism were studied by using scanning electron microscopy and X-ray photo-electron spectroscopy before and after polishing, respectively. The results showed that the chemical reaction between the rare earth metal and carbon diffused into the polishing plate took place and the rare earth metal could clear the carbon element effectively during the super-high speed polishing.

Abstract: A new ZrO₂ nano-composite ceramic tool and die material was prepared with vacuum hot pressing technology. The friction and wear behaviors of ZrO₂ nano-composite ceramic tool and die materials in sliding against 45 chilled steel rings under dry friction were investigated by using an MMW-1A abrasion wear tester. The mechanical properties and the friction and wear properties of the composites with various compositions and contents were studied. It is indicated that the changing trends of the wear rate and the mechanical properties of the composites with the change of TiB₂ and Al₂O₃ contents are roughly the same, but the friction coefficient is not obviously. The friction and wear properties and the mechanical properties are finer when the TiB₂ and Al₂O₃ content is both 10%.

Abstract: This paper explains the results of a systematic dry hobbing experiment performed on a general mechanical transmission type of hobbing machine. The HSS hobs with different combinations of coat materials and coating states display significant variations in tool life. A TiN coating hob demonstrates the best cutting performance although the coating cost is the lowest. Furthermore, some meaningful discussions related to the dry hobbing mechanism are also presented.

Abstract: An edge chipping experiment under static load is adopted to study the Kaiser Effect during the failure process for engineering ceramics. The mechanisms inducing Kaiser Effect are discussed. Some AE signals during the course of Kaiser Effect are analyzed. The results show that there’s obvious Kaiser Effect during the failure process of edge chipping; count, energy and amplitude can be well used to describe the Kaiser Effect. The surface metamorphic layer remained on the ceramic surface during the course of machining is the main factor for Kaiser Effect. Edge distance and mechanics characteristic are the important factors for Kaiser Effect. The study on Kaiser Effect of edge chipping has provided some guidance to prevent edge chipping of engineering ceramics.

Abstract: A difficult-to-machining material, cast supper alloy K24 has been cut with two different methods, milling and abrasive waterjet (AWJ). It is shown that milling is characterized by high tool cost, low efficiency, and good surface roughness while abrasive waterjet brings high efficiency and worse surface quality. The results have proven that the combination use of AWJ and milling is an efficient way in cutting K24.

Abstract: It is always the difficulties for micro hole machining in the machine manufacturing industry, even more in the defense industry. The vibration drilling new craft, with the incomparable advantages in micro hole drilling, is different from the common one. The precision NC micro hole vibration drilling machine is developed, and the micro hole drilling experiments are conducted. The vibration drilling can not only improve the drill life more than ten times compared with the normal one, but also improve the centering ability and position precision.

Abstract: An experimental study of a radial-mode abrasive waterjet (AWJ) turning of AISI4340 high tensile steel is presented. The major process parameters, i.e. feed speed, waterjet pressure, abrasive flow rate, nozzle tilt angle, and workpiece surface speed, are considered in a statistical experimental design. The advantages of the radial-mode AWJ turning over the offset-mode turning include maximum jet energy utilization, high surface speed, a variety of nozzle tilt angles and small nozzle standoff distance, to enable high material removal rate (MRR). It is found that the depth of cut is considerably increased when large nozzle tilt angle and high surface speed are used. It also shows that feed speed and waterjet pressure are the two most significant parameters to control the MRR. This preliminary study suggests that the radial-mode AWJ turning is feasible and can yield high material removal rates. Future research to advance the knowledge about this new machining process is also proposed.

Abstract: In this paper, surface residual stress in the cold working tool steel (Cr12MoV) by EDM was investigated by X-350 X-ray residual stress analyzer and method of DJP-2 electrolytic polishing instrument to remove layer by layer in the different EDM conditions. The results show that the distribution of surface residual stress generated not only by the peak discharge current and pulse width, but also by pulse interval. The same depth from the surface, residual stress of material after hardening is larger than the residual stress after annealing, With the different combination of tool electrode and work-piece material, the form of the discharge between two electrodes and the proportion of energy put between two electrodes are different, surface residual stress are also different. Different processing liquid for processing, the depth of residual stress generated is much the same, but closer to the surface, the worse the cooling capacity (quench degrees) and surface physical properties of processing fluids, the greater the residual stress. EDM, the generation and control of the surface residual stress depends on the choice such as processing power criteria, work-piece material, electrode materials and processing liquid. Surface residual stress after processing can be used to eliminate high-temperature heat treatment.

Abstract: This paper reviews the background and significance to investigate the high-speed speed blanking process modeling simulation and optimization of large blanking machine equipment for CNC uncoiling, leveling and shearing line. And a powerful tool has been providing to of heavy machinery optimal design specifications. The finite element model of beam structure has been established by using a three-dimensional modeling software UG NX4.0 CAD and finite element analysis software ANSYS. Then the static and dynamic characteristics results of the whole beam structure have been simulated. On the basis of analysis results, the optimal static and dynamic performance of square cross-section of the beam structure has been obtained. Drawings at the design stage of large blanking machine equipment for NC uncoiling, leveling and shearing line, the use of finite element theory and modal analysis theory, the structure of the blanking machine static and dynamic performance analysis and prediction using optimal design method for optimization, the new machine to improve job performance, improve processing accuracy, shorten the development cycle and enhance the competitiveness of products is very important.

Abstract: The micro growth process and characteristics of deposited material in micro EDM deposition are researched in this paper. In the initial stage of the deposition the deposited material is not an even layer in the diameter direction of tool electrode. The emergence of deposited material will affect the next pulse discharge distribution between tool electrode and workpiece. A micro cylinder with the diameter of 85µm, height of 255µm formed successfully with the fine surface quality using the tool electrode diameter of 200µm. It has shown that micro EDM deposition process has the ability to fabrication more finer micro structures with thinner electrode. The characteristics of deposited material including bonding behavior between deposited material and workpiece, energy spectrum analysis, hardness test and resist compression test of the deposited material have been tested. Results show that the deposited material has compact microstructure and bonds close to the workpiece, which can be used in the occasion of withstanding compress.