Key Engineering Materials Vols. 315-316

Abstract: The nanoscale functional thin film with the affinity to acrylic rubber was formed on the surface of a high ductile spheroidal-graphite cast iron by means of polymer plating of 6-diallylamino-1,3,5-triazine-2,4-dithiol monosodium salt. The direct joining of acrylic rubber to the cast iron was achieved with the functional nanofilm during curing. High peel strength adherend of the rubber/cast iron was obtained with suitable film thickness and good film quality under curing at 453 K for 18 min. When the film thickness was 8.53 nm, peel strength of the adherend was high to 4.9 kNm-1, and its broken-out section was rubber cohesive failure. The film thickness considerably affected peel strength and rubber coverage. Moreover, the current density of polymer plating had largely influence on mass and quality of thin film, thereby on joining property of acrylic rubber to the cast iron. The good joining property results from chemical bond within interfacial layer of acrylic rubber chain and reactive groups of nanofilm polymer-plated on the surface of cast iron.

Abstract: Aiming at the problem of image recognition in the process of defected chip generation of automatic machining, fuzzy category methods of RBF net and eight neighborhood Euler numbers are researched in this paper. They are based on fuzzy theory and neural net. The gradient steepest descent of optimization theory is used and aberration is minimized by step between required output and actual output. By modifying studying algorithm, recognized capacity is increased. This method is tested in Matlab platform. It can be concluded that fraction of chip image under sophisticated surrounding may be recognized accurately through this net.

Abstract: In large-area HFCVD system, substrate temperature is a key factor which deeply affects the quality of diamond films. It is hard for traditional PID method to control the temperature efficiently. This paper presents a genetic- based PID control scheme for the control of in HFCVD system. Computer simulation and experiment on the system are performed. The results show that the controller designed upon GAs has good dynamic quality and steady-state precision, could meet well the need of the temperature control during depositing diamond films.

Abstract: B-doped diamond is an excellent grinding material owing to its high hardness, oxidation resistance and chemical inertness as well as low resistance. The recent developments of Boron doped conductive diamond has further increased the scale of diamond applications including the manufacture of electrically conductive grinding wheel or the use as an electrode in EDM. The unique electrochemical properties also attract the researchers’ attention on the applications of electrode, sensor and detectors etc. This paper presents a viable technology that high boron doped diamond is synthesized under high pressure and high temperature using B-doped GICs as carbon sources. The synthetic diamond grains with electrically resistivity of 2
cm are sufficiently conductive for electrochemistry measurement. Cyclic voltammotry was performed to evaluate the electrode characteristics of diamond powder. The results shows that B-doped diamond powder electrode is electrochemically stable in the supporting electrolytes such as 0.1M KCl, 0.5M Na2SO4 and 0.1M H2SO4 over a wide potential range. The level of background current is very low. The electrode reaction is quasi-reversible in 0.5M Na2SO4 containing the ferricyanide-ferrocyanide redox couple.

Abstract: Laser shock forming of metal sheet usually effects on the surface of work-piece in normal direction by laser beam, and produces shock wave force which is vertical to the surface of work-piece. But it is difficult to shock in normal direction during processing on the surface of forming camber, so it needs to study on oblique angle laser shock processing. LD31 forging aluminum alloy sheet is shocked by Nd-glass laser in the paper, model and mode of oblique angle laser shock processing is found, and transmitting characteristics of plasma stress wave is discussed. The experiment results show that the angle between input beam and sample normal is bigger, component of forces that parallel with sample surface is bigger, the deformation eccentricity is bigger and bigger. When the angle is bigger, the area of laser beam spot becomes bigger too, energy density becomes smaller, deformation becomes shallower.

Abstract: This paper presents an energy saving electrical discharge machining (EDM) pulsed power supply, the principle of which is introduced. This pulsed power supply possesses no current-limiting resistors used in conventional EDM pulsed power supplies and no energy storage inductors applied in most other energy saving pulsed power supplies. Direct current from DC power supply is chopped to form many branches of paralleling spike pulse currents and the current branches are then combined into the desired pulse current for EDM machining through cyclic superimposition. The calculation method of energy loss is then analyzed. The short-circuit and contrastive machining experiments proved that the new pulsed power supply was capable of performing stable machining with higher machining efficiency and less main-machining-circuit energy loss than those of conventional EDM pulsed power supplies.

Abstract: The radome made of special ceramic is a workpiece needed to be machined precisely. The machining precision of the exterior contour of the workpiece effects the performance of the radome directly. Around improving on machining technology of the traditional radome’s exterior-surface, the creep feed surface grinding by cup wheel based on line enveloping is presented in this paper. Due to combining the advantages such as large material removal rate, high machining precision and high efficiency of creep feed grinding and the superiority of cup wheel, the workpiece with perfect surface quality can be reached. Furthermore, the mathematics model of the geometric locus of grinding wheel head rotating center is established by using the linear interpolation algorithm, with a combination of the equal-space and equal-error method. The existing NC grinding machine with 2-axis simultaneous motion is transformed into 3-axis simultaneous motion (adding an axis of rotation B) and its feasibility applied to the exterior contour machining has been verified.

Abstract: The analysis on load characteristics and stress state of bearing races shows that the roll path and outside layer of a bearing race are the main part to bear the load, and that residual tensile stress is often found on workpiece surface. For the purpose of improving residual stress state on machined surface of a bearing race, a method of pre-stress hard cutting is put forward. In this paper, the principle of pre-stress cutting is introduced, and method of loading stress on bearing races, together with the calculation for pre-stress, is analyzed. A set of device with expanding mandrel for realizing the process is designed too and an experiment of pre-stress cutting is carried out on a lathe with PCBN tool. The experimental results show that, by using this method, we can get residual compressive stress on machined surface layer of a bearing race and increase the quality and contact fatigue life of bearing.

Abstract: Hybrid sleeve bearing is widely used in high speed principal axis system. Numerical analysis on a spiral oil wedges hybrid sleeve bearing of high speed principal axis is investigated in this paper. The finite differential equations of Reynolds, film thickness and velocity in an oblique coordinate system are obtained. By means of the finite differential method, loading capacity, pressure distribution, and stream of lubricating oil of the hybrid sleeve bearing are computed and analyzed. The results show that spiral oil wedges can produce the flow separation between hot oil and cold oil, and avoid the oil heated repeatedly. With the increase of eccentricity and decrease of spiral angle, the loading capacity of the bearing increases.

Abstract: The development of the capability to machine glass materials to optical quality is highly desirable. In this work, the deformation characteristics of brittle materials were analyzed by micro and nano indentations. Diamond cutting of optical glass BK7 was performed in order to investigate the tool wear mechanism in machining of brittle materials and the effect of tool vibration on material removal mechanism. The tool wear mechanism was discussed on the basis of the observation of wear zone. Ductile-mode cutting has easily been achieved with the application of ultrasonic vibration during cutting of glass. It was confirmed experimentally that the tool wear and surface finish were improved significantly by applying ultrasonic vibration to the cutting tool.