The purpose of the present study is to develop a new technology to raise the bond strength between ceramic coatings and bulk metals. A surface just after being cut is chemically active because of its high cleanliness and a moderate temperature above 100°C. On the basis of these characteristics of metal cutting, this paper proposes the clean-cut plasma spraying in which ceramic particles melted by a plasma heat source are sprayed on the machined surface immediately after the cut. When using a structural steel for the bulk metal and an alumina for the spray powder, the alumina ceramic coating attains to a thickness of 0.31 mm/pass, a hardness of 76 (SUPERFICIAL 30-N) and a bond strength of 38 kgf/cm2. Thermal cycling and thermal shock tests of the coating also show that the cleancut spraying is superior to the conventional spraying where steel ball blasting is used for a pre-treatment.
The feasibility of microwave sintering of electronic ceramics was investigated using a heating control system. This system comprises a klystron amplifier with 6 GHz band, a single mode rectangular cavity for sintering ceramics, and a controller for operating the heating condition. Eight kinds of electronic ceramic powders, Al2O3, AlN, TiO2, stabilized ZrO2, ZnO, PZT, PLZT, and BaTiO3, were prepared as test samples. These powders were compacted into a cylindrical form of 6.6 mm diameter, followed by cold isostatic pressing (CIP). Then, they were sintered in the cavity with either air or nitrogen gas. ZnO and stabilized ZrO2 were easily sintered in air, and their densities were the same as the theoretical densities. Especially, ZnO could achieve a high density of over 95% of the theoretical with a sintering time of only 5 sec. On the other hand, the microwave sintering of PZT, PLZT, and BaTiO3 was difficult because uneven heating and melting occurred due to thermal runaway. However, by covering the samples with a silicon carbide tube, the thermal runaway could be prevented. The sintered PZT had uniform microstructure with over 98% of the theoretical density.
This investigation examines the surface crack and the residual stress causea by machining of cemented carbides used for cutting tool. These were evaluated from the bending strength, the microcrack length and the fracture toughness on the basis of fracture mechanics by using the transverse rupture test. Within tested materials, the surface crack length was 6 to 20μm. This value was smaller than thickness of deformed layer acting compresive residual stress. It is found that the surface crack length decreases with decrease in grain size of grinding wheel, and with decrease in depth of cut in grinding operation. Therefore the bending strength increases with decreasing grain size and depth of cut.
This paper deals with the characteristics of TiC coated on the tool steel of SKD11 by CVD method. The surface residual stress was measured by the X-ray stress measuring method. Also the characteristics of adhesion by the scratch test and wear resistance by the wear test were evaluated. Furthermore, the effect of heat treatment (quenched at 1020°Cand then at 450°C or 520°C) after CVD on these characteristics was considered. The results are as follows : (1) The residual stresses of TiC layer are compressive. However there is difference in values between after quenching and after tempering, and further there is also difference in values between in case of tempering at 450°C and tempering at 520°C. The stresses were -3.17GPa and -2.94GPa, respectively. These values were nearly equivalent to the calculated values of thermal stress. (2) Acoustic emission signal was detected corresponding with peeling off or damage of TiC layer. Also the critical load is subjected to the influence of substrate. The harder the substrate, the larger the critical load. (3) Wear resistance of SKD11 is extremely improved by means of coating CVD-TiC. When OHGOSHI type wear test is applied and TiC layer is very thin, not only the wear resistance of TiC layer but also the substrate of SKD11 is evaluated.
In this investigation, a centrifugal separator was used to separate grinding chips from grinding fluid. In order to clarify the efficiency of the centrifugal separator, separating experiments were carried out by changing grinding chips (FC, ceramics), its concentration and flow rate of the grinding fluid. They were measured by means of sample bottle way and coulter counter way, and the methods were compared with each other. Furthermore, the minimum size of separated particles by the centrifugal separator was investigated theoretically and experimentally. As the results, the fluctuation of the separating efficiency by sample bottle method was larger than that by coulter counter method. The separating efficiency was increased with the increase of concentration.The influence of flow rate on the separating efficiency was smaller than that of concentration. The minimum size of separated particle was attended to increase with increasing flow rate rather than increasing concentration.It was clarified that the separating efficiency of centrifugal separator was considerably high and enough to use in grinding operation.
This paper describes the fracture mechanism and the prevention of crack propagation in laser-processing of the hot-pressed silicon nitride ceramics using the pulsed YAG laser. The crack formation mechanism is successfully explained by the thermal stress and fracture strength distribution. The laser pulses controlled at below the critical duration and frequency are effective for the purpose of crack-free processing because the thermal stress is localized only in the laser-heated shallow region.
The blade being quite free from deflection is in an unstable state in the outer-blade slicing process and easily deflected by a slight lateral force. The deflection causes a participation of the side face of the blade in grinding, followed by an increase of the lateral grinding force. It makes further deflection of the blade itself. The object of this paper is to clear how both sides of the groove are generated by the blade deflected because of a lateral grinding force. For the purpose, the state of a blade in slicing was estimated from the geometry of the groove obtained by interrupting grinding in the middle of a pass. That is discussed in relation to three components of the grinding force measured at the same time. Furthermore, the effect of the grinding conditions is studied experimentally on the geometry of the groove and the cut-off accuracy. The cut-off surface on the convex side of the blade showed a higher flatness. On the contrary, that on the other side showed a concave shape to the vertical direction. The kerf-loss was mainly generated on the concave side of the blade, andbecame larger with an increase of the asymmetry of the blade section and the projection of the blade from the flange.
This paper deals with the improvement of hole accuracy by piloting drills. The piloting drills have two short cutting edges and a piloting part on the projection of twist drill point. Experiments showed the following results. These drills improve the roundness at the hole entrance, because the wandering motion of drills can be suppressed by a short chisel edge and has already damped under the effect of a piloting part when the corners of primary cutting edges enter workpiece. In the rotating drill-stationary workpiece system piloting drills produce smaller hole oversize, hole deviation of axis and its scatter at the hole entrance than conically ground drills. Further improvement of them can be obtained by two-step feed, which consists of a very small feed rate and an ordinary feed rate before and after the primary cutting edges enter workpiece, respectively. The improvement of hole accuracy results from small oversize of pilot hole at a small feed rate. Longer piloting part is desirable from the viewpoint of the reduction in hole oversize.
This paper describes the principle and performance of a novel interferometer developed for the measurement of differential height of an oil manometer for use in the range up to 1 kPa. The heterodyne interferometry using Zeeman stabilized He-Ne laser was applied to detect the displacement of oil surfaces which reflect laser beam directly. A system of double U-tube and double interferometer was introduced and developed in order to compensate errors caused by thermal and mechanical changes. The performance of the system was estimated from the experiments in which silicon oil of 100 mm2/s kinematic viscosity was selected as a manometer fluid. The short term and long term stabilities of zero-point are evaluated as standard deviations of 0.001 μm in 5 seconds and 0.01 μm in 3 days, respectively. The hysteresis of zero-point is 0.01 μm after 1 000 Pa pressurizing, during which the oil surfaces can be moved with a speed of up to 25 mm/min. The overall uncertainty of this system is estimated to be 0.026 μm.
This paper describes two types of piezo-driven translation mechanisms, which are composed of a flexure-hinged linkage and cut from a monolith. The natural frequency and accuracy of motion of the mechanisms are examined in detail to assess the applicability of both of the mechanisms to the scanner of STM (scanning tunneling microscope). Design formulae of the natural frequency, derived from the strain energy method, are presented to optimize the mechanism design for maximizing the natural frequency. Experimental investigation confirms the validity of the formulae derived. It is demonstrated that a scanning range of 65μm is attained with a parasitic rotation smaller than 0.3 arcsec and natural frequencies amounting to 508 Hz and 2508 Hz in the directions parallel to and perpendicular to the motion of moving platform, respectively.
In this study, in order to change the overlapping ratio the speed of test piece and abrasive paper were changed widely and a series of experiments were carried out. And it was examined that the overlapping ratio had an effect on wear characteristics. Results obtained are as follows. (1) In the X-direction when the velocity ratio is from 0 to 3, the wear rate is dependent on sliding speed of abrasive belt, and when more than 3, the wear rate is dependent on vibrational velocity. (2) In the Y-direction when the velocity ratio is from 0 to 2, the wear rate is dependent on the rubbing directions, and when more than 3, the wear rate is dependent on vibrational velocity.
A new optical method for the proximity sensing is proposed. The distance from the object surface to the sensor is measured by using the thermal wave generated by the light absorbed at the surface. The proposed method is useful for the surface with a high absorption coefficient. Moreover, the technique can be applied to the specular surface as well as the rough surface if the light is absorbed somewhat at the surface. A modified mirage technique was used for monitoring the amplitude and phase signals of the thermal wave. In the experiment, a black rubber plate and an aluminum mirror were used as the objects. The accuracies of measuring distance are discussed.
For automatic CAD data exchange, a method was proposed based on data format which consists of data structures, algorithms and data. This method uses a three schema architecture which consists of an application schema, conceptual schema and physical file data schema. The conceptual schema plays a role of neutral data structure between an application schema and physical file data schema. An experimental system based on the above method was developed. Then a test regarding 2-D CAD data exchange was demonstrated. From the experimental results, it is recognized that the proposed method is useful for the CAD data exchange.
It is well known that the solution of the inverse kinematics for robotic manipulator requires a lot of labor and time. In this paper, they propose a new method to automatically generate the closed form inverse kinematics solutions for most industrial robots efficiently. This method is based on the subdivision of rigid displacement into elementary subspaces which have invariant geometric properties. Using the invariant geometric properties of the elementary substructures, kinematic invariant relations are obtained, which are independent of the joint variables of the substructures. These relations generate the symbolic inverse kinematic solutions by computer algebra software Mathematica. Their program has successfully solved the inverse kinematics of more than ten typical industrial manipulators.
Robust differential equation solvers which can be applied in tracing intersection curves of surfaces are discussed and recommended for use in regions very near to singular points. And also behaviours of intersection curves around the singular points are analyzed, because the differential equations do not hold at the singular points where normal vectors of the two surfaces become parallel. With these two approaches tracing of intersection curves can be confidently performed even in critical cases and the tracing time is automatically adjusted in accordance with difficulty of the tracing. Numerical examples of critical cases are shown.
This paper presents a method of bottom up processing for separating all drawing elements in a whole recognition system for mechanical drawings. This is the second report succeeding the first one which mainly dealt with a method of separating thick- and hair-lines using line width and the structural representations of thick-lines. However, this methed can be applicable only to the drawings which keep the JIS drawing rules vigorously, especially about line width. In this paper, we propose another approach which can be applicable to wider range of mechanical drawings. The method mainly utilizes geometrical and topological features and uses line width additionally. The whole algorithm is shown to separate all line elements, i. e., dimension lines, projection lines (temporarily separated), center lines, hidden outlines, leader lines, visible outlines, projection lines (finally separated) and characters, in this order. Some experimental results applied to sample drawings in a book of mechanical drawings are finally shown.