Results of temperature measurements by analysis of the thermal emission spectra generated during grinding and subsequently transmitted through partially stabilized zirconia workpieces are presented. Portions of emitted visible and near‐infrared spectra were collected with spectrometers. Source temperatures were determined by fitting the scaled spectrometer output spectra to blackbody curves. Simulations showed that the effective temperatures determined by this method will be strongly biased toward hot‐spot (flash) temperatures, which are expected to occur at the grinding grit–workpiece interface. Hot‐spot temperatures on the order of 3000 K were obtained for grinding with both SiC and diamond wheels. These high temperatures modify the grinding process and the phase content of grinding chips.
Pure iron is a kind of high plasticity and toughness material. In the process of cutting pure iron, the tool wear is very serious. In this paper, three kinds of cutting tools KC5010, K313 and 1105 are used in the cutting pure iron process and the tool wear tests in dry cutting condition with different cutting parameters have been carried out. According to the results, the tool wear mechanisms and tool life of three kinds of cutting tools have been compared and analyzed. It is concluded that the tool life of K313 is better than KC5010 and 1105 and the three kinds of tool mechanisms are primarily adhesion wear, diffusion wear and oxidation wear.
Thin wall spherical shell is easy to deform at the process of turning because the low rigidity. In order to improve process precision of the thin wall spherical shell, the thought increasing the workpiece technology stiffness is put forward, which the magneto-rheological fluids (MRF) is filled inside the thin wall spherical shells as strengthening phase transition material. In magnetic field, MRF can transform from fluid to solid and solid back to fluid rapidly. According to the thought, the fixture designed is applicable for the thin wall spherical shells process precision. The clamp stiffness can be controlled and the MRF can be used many times. In order to get uniform intensity of the magnetic field in MRF, the special magnetic device is designed which is based on the variable MRF thickness and the magnetic field distributing is analyzed and optimized. The fixture based on MRF will help to improve machining precision of the thin wall spherical shells.
In the process of precision turning parts of pure iron, tool wear is very serious. The tool wear has been a key factor to affect the precision of parts. In this paper, the experiments of turning pure iron by use of carbide tools have been carried out in different cooling and lubricating conditions. Based on the analysis of the SEM pictures of carbide tool wear morphology and the compare of the carbide tool wear degree in different cutting conditions, it can be concluded that the carbide tool wear mechanism are mainly adhesion wear and fatigue wear and the benefit of lubricating condition is better than cooling condition to improve the tool life. According to the results, the application of CMQL technology can effectively reduce tool wear in turning pure iron.
Magnetorheological (MR) fluids can transform from fluid to solid and back to fluid rapidly in magnetic field. It is a novel intelligent phase transition material. In this study, MR fluids are filled inside a thin wall spherical shell as phase transition material to improve the workpiece stiffness. A fixture structure based on MR fluids for the thin wall spherical shell precision machining is designed. The fixture stiffness can be controlled and the MR fluids can be used many times. The MR fluid as strengthening material is developed and the amount of metal powder in MR fluids is 52% by volume and the performance of MR fluids is measured. Based on electromagnetic principle, a special magnetic field is designed and the magnetic field distributing is analyzed and optimized. The thin wall spherical shell using the designed fixture is turned in CK7820B lathe. The cutting experiment result shows that the fixture based on MR fluids can improve the workpiece machining precision.
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