Papers by Keyword: Seizure

Abstract: Forward rod-backward can combined extrusion test was used to investigate the tribological properties of Ti-6Al-4V titanium alloy with oxide film at cold and warm forging conditions. 0.08 and 0.10 µm-thick oxide films were formed on the test piece by atmospheric oxidation treatment. A friction test was performed without using lubricants. As a result, the oxide film was effective to prevent seizure at cold forging condition, where the friction coefficient was estimated as about 0.15. However, at warm forging condition, a decohesion of the oxide film and seizure occurred, where the estimated friction coefficient was larger than that at cold forging condition. Furthermore, thickening the oxide film was effective against the decohesion and to reduce the friction coefficient.

Abstract: Cladding is the bonding together of dissimilar metals. One of clad products is the titanium clad steel sheet. It is effective to cover with pure titanium sheet to improve the corrosion resistance of the steel sheet. Titanium clad steel sheets are often achieved by rolling sheets together under high pressure. In the current study, the blank comprising three laminar non-bonded sheets, such as the titanium/steel/titanium sheet, is arranged in the die. The formability of pure titanium clad sheet by multistage deep drawing was investigated to enhance corrosion resistance of steel cup. In the experiment, the blanks were pure titanium sheets JIS1-TP270, JIS2-TP340, ultralow-carbon steel SPCC, and stainless steel SUS316L. The initial thickness of the sheet was 0.2 to 0.5 mm in thickness. The blank diameter was 70 mm. The blanks are merely adjacent sheet; however, not joined with each other. In the deep drawing process, a hydraulic press was used in the experiment and the forming speed for the press was about 10 mm/min. The lubricant used was the solid powders of molybdenum disulfide. For the prevention, pure titanium blank was treated by oxide coating. The conditions of heat treatment were annealed at 973 K for 3.6 ks to 7.2 ks. By oxide coating, the titanium sheet has sufficient ability in preventing the seizure in multistage deep drawing. The drawn cups of the three-layer laminated sheet were formed. The seizure did not cause. The oxidatively-treated titanium sheets have sufficient ability in preventing the seizure. In addition, the clad cups until 6th stage were formed by multistage deep drawing. Long clad cups were successfully formed in multistage deep drawing process.

Abstract: In this paper, the thermal failure (seizure or melting) of hybrid radial bearing (PEEK ring-PTFE composite retainer and alumina ball) under rolling contact fatigue test was investigated. For effective operation of equipment in various environments such as dirty, harmful or corrosion situations, the radial PEEK-PTFE hybrid bearings were produced by machining. The PEEK accumulation layer containing carbon graphite was formed on the raceway of bearing's inner ring at 1200-1500 rpm rotation speed. Due to the self-lubrication of the PEEK composite accumulation layer as solid lubricant, the operation temperature in the hybrid bearing was lower than that of all PEEK radial bearing, and the load capacity of the PEEK bearings could be improved. Moreover, it was found that the PEEK composite film which is formed from the PEEK composite layer protected the raceway from the friction heat.

Abstract: This paper deals with the formability of pure titanium sheet in square cup deep drawing. Pure titanium has very excellent corrosion resistance. In the metal forming process, pure titanium has very good ductility in cold forming. The normal anisotropy of pure titanium is very high. Therefore, the property is suitable to the sheet metal forming, such as deep drawing process. However, the most important problem is that the occurrence of seizure becomes remarkable in severe forming operations. Many investigations on the effect of processing conditions on the seizure of titanium were carried out. In the present study, the formability of pure titanium sheet in square cup deep drawing was investigated. For the prevention, pure titanium sheets were treated by heat oxide coating. The fresh and clean titanium is not in direct contact with the die during the forming due to the existence of the oxide layer. The material was pure titanium sheets of the JIS grade 2. The initial thickness of the blank was 0.5 mm in thickness. In the deep drawing process, the sheets were employed and a flat sheet blank is formed into a square by a punch. Forming of sheet by multi-stage deep drawing was tried. Various cups were drawn by exchanging the punch and die. The die was taper without a blankholder in the subsequent stages. The effects of the intermediate annealing and tool shape on the occurrence of seizure in square cup deep drawing were also examined. The square cups were successfully drawn by heat oxide coating. The coating of titanium sheet has sufficient ability in preventing the seizure in multi-stage deep drawing operation. The results of the present study revealed that the pure titanium square cups were successfully formed by using heat oxide coating treatment.

Abstract: The conventional and innovative surface technologies are applied to sheet metal stamping dies in order to produce a composite material with properties unattainable in either the base or surface material. To select proper materials for forming dies the systematic evaluation of dies materials, their heat treatment and coatings are required. This paper deals with evaluation of plasma sprayed coatings Cr₂O₃, Al₂O₃ and WC12Co by pressure plate-ring test (tester T 05) and deep drawing process. Friction coefficients and seizure of these coatings were studied under dry and wet friction conditions. For different types of die rings (with and without ceramic coatings) the punching forces were measured during deep-drawing process. The results show that the main advantage of application of plasma sprayed coatings on the die contact surfaces under wet friction conditions compare to dies made of the tool steel may be the increase of seizure resistance of stamped part surface. The more significant difference in the friction coefficient values was not observed.

Abstract: This paper presents the results of research into the effect of the use of an additive to the lubricating oil SAE 15W/40 on the lubricating properties (standardised tests), i.e. the weld point Pz, last non-seizure load Pn, load-wear index Ih, and seizure load Pt. The friction pair consisted of four balls and the tested lubricant. Moreover, the impact of the use of the lubricating oil (non-standardised tests) on tribological properties such as friction force, wear, and the temperature of the friction area for the friction pair C45 steel/210Cr12 steel, was explored. The additive contained copper and lead particles of the size of a few micrometers. The tests helped to determine the effect of the use of the additive to the lubricant on the formation of the operational surface layer. The results were used to build a model of the boundary layer formed as a result of the additive to the lubricating oil.

Abstract: During maintenance operations, technicians have to work as quickly as possible. But they are often stopped during disassembly by blocked bolts or studs. This paper examines causes of blockage and suggests new method for disassembling bolted joint in this case. Several methods are analyzed and tested with finite element simulations. An experimental protocol to test a new disassembling method is also introduced in this paper

Abstract: Nowadays, due to strict environmental requirements, the automotive industry has been reducing vehicle weight in order to minimize the CO2 emission. This had led to an increase in the demand for plastic car parts as a replacement for formerly metal components. Poly ether-ether-ketone (PEEK) has a high glass transition temperature of 143°C, good friction and heat resistance, and can be easily machined. Due to these characteristics, PEEK is already being widely applied in the production of various car parts, such as seat adjustment parts, transmission parts, oil-pump parts etc. In the present study, PEEK bearings were produced by machining and their rolling contact fatigue (RCF) under non-lubricated conditions was investigated. Under high radial load, seizure in the inner bearing part occurred while under low radial load, there was failure by adhesive wear. Exposed to medium load between 85.6N and 93.1N, however, the bearings achieved relatively long lives of over 1.0x10E6 cycles, as well as a unique feature of self-lubrication that rid the raceway of micro depressions, deposits or smearing.

Abstract: The pure titanium long-cups were formed by preventing the seizing in cold multi-stage deep drawing processes. For the prevention, pure titanium sheets were treated by heating oxide coating. The coating is very effective in preventing the occurrence of seizure and galling. The fresh and clean titanium is not in direct contact with the die during the forming due to the existence of the oxide layer. In multi-stage deep drawing, pure titanium sheets of the JIS grade 2 was employed. Various cups were drawn by exchanging the punch and ringed die. The die was flat in the first stage, and was taped without a blankholder in the subsequent stages. The effects of the coating conditions on the occurrence of seizure in multi-stage deep drawing were examined. It was found that the coating titanium sheet has sufficient ability in preventing the seizure in multi-stage deep drawing processes. The pure titanium long-cups were successfully formed by a multi-stage deep drawing operation in cold.

Abstract: The embedding parameters of electroencephalogram (EEG) time series, i.e., the embedding dimension and delay time, are used together as the input features of artificial neural network for distinguishing between normal and epileptic EEG time series. Cao’s method and mutual information method are applied for computing the embedding dimension and delay time of normal and epileptic EEG time series, respectively. The probabilistic neural network (PNN) is used in this paper for distinguishing between normal and epileptic EEG time series. The results of the simulation show that the overall accuracy as high as 100% can be achieved by using the method proposed in this paper, and that the accuracy obtained based on the both parameters is better than that obtained based on each of the two parameters respectively.