Crankpin grinding differs from ordinary cylindrical grinding processes. Because, the center of pin portion has extreme offset from the center of journal portion. So, the left and right work spindles are required to have a mechanism for clamping and driving the journals by means of eccentric chucks on both sides of the crankshaft. With such an eccentric work spindle drive system, synchronization accuracy of the work spindles has influence on the roundness, phase accuracy, and several other characteristics of the crankpin grinding accuracy. To cope with these problems, it was developed a servo synhro-drive system, which drives the work spindles independently with AC servo motor, compensating for the phase difference between the two work spindles with the NC system. This paper first discusses several factors which prevent the achievement of high-speed high-accuracy crankpin grinding when the conventional work spindles is used. Secondly, it proposes the newly developed work spindles using a servo synchro-drive system for the purpose of achieving high synchronization accuracy. Finally, it describes the grinding results obtained by crankpin grinder equipped with the newly developed work spindles.

View full abstract

The possibility of a film formation based on impact adhesion of solid particles was investigated by making tungsten submicron-sized particle beam vertically irradiate at the velocities of several hundreds m/s onto silicon substrate. The deposition phenomena of impact particle were examined by evaluating geometrical parameters of each deposit, and it became clear that relatively small particles are selectively deposited and accompanied by severe plastic self-flow and slight penetration into substrate, and the deformation degree depends on the impact velocity. As for the interfacial characteristics of film-deposited silicon, the tensile adhesive strength superior to the fracture strength of silicon and nearly ohmic current-voltage characteristics are observed which are similar to thermally joined junction, with both of pull testing and point-contact diode measurement. These suggest metallurgical change at interfacial layer of silicon.

View full abstract

Vacuum-gas nitriding process is an effective method for controlling the thickness of nitride layer on the surface of hot die steel. This study has been carried out for increasing the life of die steel. Thermal fatigue characteristics of samples treated by the vacuum-gas nitriding process were evaluated by means of thermal fatigue test, erosion test and X-ray analysis. Fe_2-3N nitride layer was not observed by the X-ray analysis in the surface layer of the sample. The hardness of sample surface was in the range of HV 800900, which was lower than that of the tufftriding sample, i.e., HV 12001400. Erosion resistance was lower than that of tufftriding sample. It was found that the thermal resistance increased by the vacuum-gas nitriding process and the nitrogen concentration in the diffusion layer formed by the process did not change during the thermal fatigue test.

View full abstract

Generally, cermets are mainly used for finish machining tools of the carbon steel. However these tools are used at speed of 200 to 250m/min, and they have short lives. Higher cutting speeds and longer lives are required for higher efficiency. It is expected that this domain can be achieved by using new ceramic tool. In this report, the wear and chipping resistance of developed Ti (C_0.5, N_0.5) -TiB₂ and Ti (C_0.5, N_0.5) -Cr₃C₂ based ceramic tools were studied when turning a carbon steel, bearing steel and stainless steel.In dry cutting, the tool lives of these Ti (C_0.5, N_0.5) based ceramic tools are longer than those of commercial tools such as cermet and Al₂O₃-TiC ceramics when turning a carbon steel at high speed finish cutting conditions, especially Ti (C_0.5, N_0.5) -30%TiB₂ ceramic tools and Ti (C_0.5, N_0.5) -20%Cr₃C₂-1%8₄C ceramics tools exhibit excellent cutting performance. Also, it was investigated that failure of ceramic tools occur when they go away from workpiece after cutting as exit failure in interrupted cutting.

View full abstract

The first report described a fundamental concept of friction from atomistic aspect and the calculation of frictional force based on the proposed concept in an elastic contact condition The results of calculation can be summarized as follows. Assuming that the contact area is constant, the frictional force is not influenced by the contact pressure in an elastic contact condition. Assuming also that interatomic potential is Morse potential, frictional force is dependent on the lattice orientation, but independent on sliding direction In the case of fcc metals, the values of frictional force is strongly correlated with those of critical shear stress. This paper reports measurements of frictional force in an elastic contact condition, in order to confirm the proposed concept of friction. The frictional force betweun the tip having radius of 15-30 μm and the flat plane is measured with an electrobalance in air and in ultra high vacuum. The results agree well with the proposed concept of friction.

View full abstract

Mechanism of ultrasonic vibration tapping and its experimental results were reported in this paper Mechanism of ultrasonic vibration tapping is similar to that of Piispanen's card model, the experimental result agree with the theoretical one For the difficult machining pure alminium (A 1050), cutting torque, cutting ratio, shear angle, deformed layer etc were investigated using the quickstop device for tapping The following results were obtained In vibration tapping, tapping torque was nearly equal to frictional torque when tap was screwed into female screw, the value was about 0.05 Nm Cutting ratio and shear angle in vibration tapping with kerosene were about three times of those of conventional tapping Deformed layer of female screw was not recoganized in vibration tapping

View full abstract

A finite element modelling of machining of FRP has been developed for better understanding of the microscopic machining mechanism such as deformation and fracture of both fiber (E glass) and matrix (polyester), and the influence of the fiber direction angle and tool rake angle upon the mechanism is analyzed. The criteria of the maximum tensile stress and the modified equivalent plastic strain are assumed for fracture of the fiber and the matrix respectively. The plastic deformation obtained is concentrated only in the matrix and the deformation mode changes with increase in fiber direction angle θ : shear mode for θ=45°, extrusion mode for θ=90° and pulling up mode for θ=135°. It is also found that the increase in 8 promotes the fiber fracture in deeper location from the cutting edge, thus deteriorating the surface finish on account of the overcut. The increase in rake angle decreases the extrusion of matrix and concentrates the deformation at cutting edge when θ=90°. The fiber direction angle, however, exerts more marked influence upon the deformation than the rake angle. The analytical results mentioned above are also proved experimentally.

View full abstract

This paper describes surface finishing of zirconia ceramics by using the surface honing wheel as a bonded abrasive tool. In newly developed surface honing wheel, fine diamond grains together with copper powder are bonded by phenol resin. This wheel has a merit to obtain a scratch-free surface, since the diamond grains can sink in metal powder. In this experiment, two wheels are set on the spindle and the rotary table of a vertical grinding machine which has large stiffness. A zirconia workpiece moves between the two wheels in a circular motion. By the method that initially 125-250N is applied, surface roughness; 20nmRmax, parallelism; 0.2μm can be obtained on a workpiece. Furthermore the characteristics of the honed surface is examined by X-ray diffraction. Results obtained are as follows; Monoclinic phase which transformed from tetragonal phase by working stress can be removed by surface honing. The less the monoclinic phase, the smaller the residual stress.

View full abstract

This paper describes the grinding characteristics on high manganese steels (Mn steels) which are austenite type. The grinding tests were performed in order to estimate these grindability by measuring the radial grinding wheel wear or the grinding force and observing the working surface of grinding wheels. The results were compared with those of austenitic stainless steel which has much similarities to high Mn steels in the material properties. The main conclusions are summarized as follows : (1) In grinding of high Mn steels by conventional or CBN grinding wheels, glazing of the cutting edges due to attrition wear is clearly recognized in the former wheel but not in the latter wheels. (2) The grinding wheel wears in the CBN grinding wheels are remarkably smaller than in the conventional wheels. (3) Because of the loading of grinding wheel, grinding wheel wear on austenitic stainless steel is remarkably greater than that on the high Mn steels.

View full abstract

In this paper, we first describe the design experiment, an experimental method used to examine design processes. The results of design experiments were analyzed in two different approaches. One was to outline transitions of object descriptions and the designer's viewpoint. The other was to extract a design cycle which was a unit design process, and we found that design processes are composed of such design cycles. Secondly, we show a framework for logical formalization of design processes which is expected to serve as a basis for developing a design knowledge representation language for intelligent CAD systems. In this formalization, design processes are interpreted as deductive processes in which not only classical logic but also modal logic and non-monotonic logic are used. This framework explains experimental data obtained in the design experiment and is considered appropriate to represent design processes.

View full abstract

For the system selecting the optimum cutting conditions, subsystems have been developed to predict the trouble occurrence in dimensional accuracy and surface roughness of machined workpiece with linear evaluation functions. Variables of the functions are selected among operational characteristics and workpiece characteristics which are gathered by questionary investigation and/or interview to expert engineers, and literature survey as well. The necessity.and the linear independence of the variables under consideration are further examined by fuzzy measures in expert engineer's subjective evaluation process. The weight coefficients of the variables in the function are objectively determined by learning of machining data in the data base so that the values of the function may be calculated to yield the same order of value as those of dimensional accuracy or surface roughness in the machining data. The subsystems perform well and can be applicable to the wide range of cutting conditions.

View full abstract

In automatic welding of thin steel plates, it is difficult to detect weld line by visual sensor, because the weld line is finer and the surface tends to reflect images of arcs and surrounding apparatus. Moreover, it is important to keep the optimum arc length in welding of thin plates. Therefore, a basic welding arc robot system with a visual sensor and an arc voltage sensor controlled by personal computers was constructed, and effects of lighting methods on detection of the weld line and the effectiveness of these control systems were experimentally investigated. As the result, it was made clear that reflection lighting method is more useful than the other conventional lighting methods for the recognition of the weld line and control systems constructed are effective for automatic welding of thin steel plates.

View full abstract

An automatic method has been proposed to compensate the thermal displacement associated with the spindle running of a machining center. At the first, this method determines a mathematical model between the thermal displacements at the cutting point and the temperature changes at the major points on the machine. The mathematical model separates the thermal displacement predicted into the zero point offset and the pitch error component. An NC controller compensates automatically the thermal displacement predicted from the temperature changes on the machine using the functions of the zero point offset and the pitch error compensation. Experiments have been carried out to verify the effectiveness of the method and the results showed that the a good accuracy of a machine is maintained during long hours auto-running.

View full abstract

A new gap detection technique is developed for quarter micron X-ray lithography, whitch technique depends on an optical-heterodyne interferometry with diffraction gratings. To obtain detection accuracy as good as a few tens of nanometers, a phase signal is utilized instead of a conventional intensity signal. The gap between mask and wafer is detected by measuring the phase difference between two heterodyne beat signals generated by projecting two laser beams from-1st-order and-3rd-order diffraction directions on the mask and wafer grating marks. The gap signal with a few tens of microns cycle makes it possible to set an arbitrary wide range gap. The gap can be detected in resolution of less than 20 nm by an experimental setup. Combining this gap detection method with the relative position detection technique using symmetric optics, a 4-channel alignment system is developed for synchrotron X-ray lithography. Six-axis alignment servo control is established by combining this system with highly accurate stages. The total overlay accuracies of ± 0.05 μm (3σ) are achieved.

View full abstract

In semiconductor manufacturing apparatus, ultra precision stage mechanism is used for positioning wafer and mask. Required positioning resolution is 0.01-0.02μm and responsibility about 50 Hz to improve the alignment accuracy and productivity of lithography systems. This paper describes a synthesis method of ultra precision stage using parallel linkage mechanism, and experimental results are introduced. A basic dynamic matrix equations of the stage are derived, and then a synthesis method to decouple the interference characteristics of each degree of freedom approximately, is proposed. According to this method a stage mechanism using 6 parallel actuators comprised of piezoelectric (PZT) acutuators, pre-load mechanism and elastic hinges at one or both ends is developed. The experimental results of static and dynamic characteristics are introduced and a synthesis method is confirmed to be valid. Additionally as a performance of the stage, decoupling accuracy less than 5% (50 Hz), minimum resonant frequency 170-180 Hz, and positioning resolution less than 0.01μm are obtained.

View full abstract

This paper describes optical measuring method to obtain inner radius of transparent capillary. There are two modes as to optical path which beam refracts and transmits in the capillary. These modes are called tangential mode and one order reflection mode. The inner radius of the capillary can be obtained by measuring transmission angle and transmission distance in each mode. The angle and distance are measured automatically by using rotary table and X table assembled stepping motor controllable by a microcomputer. The optical intensity of transmitted beam is transformed into voltage by a phototransistor and the determination of the angle and distance is performed by detecting maximum voltage. In spite of optical measurement, it is not necessary in this method to measure the index of refraction of capillary material. From experimental results the accuracy of new measuring method is ±1/500 mm.

View full abstract

This paper describes the development of a load torque detection technique of stepping motors by using sensed back electromotive forces (emfs). One of the advantages of stepping motors is that the motors can be operated by open loop control. However, the stepping motor driven by open loop control method loses synchronism with input pulses when the load torque exceeds the pull out torque limit. Therefore the control system must be designed with enough margin to cope with unexpected increase of load torque. In order to use stepping motors more efficiently, detection of the applied load torque is very useful. The authors developed a new method to detect the load torque without additional torque sensors by comparing the back emfs induced in the coils of the stepping motors and energizing voltages to the coils. The influence of the load torque on the phase difference between voltages supplied to the coil and back emfs is made clear theoretically. Based on the theoretical considerations, authors devoloped and examined torque sensing method by two ways. First one is to detect time difference between input drive pulses and pulses made of back emf by comparators. The second one is to detect the phase difference continuously by processing the back emfs with drive voltages. Experimental results show the effectiveness of both methods. And as an example of application, such a control where the stepping motor changes its direction of rotation at a certain torque is demonstrated successfully.

View full abstract

This paper describes a new turning-surface roughness measuring method by slit aperture width vibration in the case of Fraunhofer diffraction. A He-Ne laser parallel beam illuminates the slit aperture formed between a test object and a reference knife edge. This knife edge is sinusoidally vibrated with a stacked piezoelectric element driven by a charge control amplifier. The zeroth order Fraunhofer diffraction light intensity is proportional to the square of the slit width, and this fundamental component intensity of the vibrational frequency is proportional to the slit width. This measurement method is characterized by non-destructive technique and obtaining a surface profile. Measurements are carried out a 2.6μm R_max turning-surface. The experimental results in the different vibrational amplitude and frequency show the same surface profile, and this method, a stylus instrument and the previous measurement method have the same surface profile.

View full abstract