The Stainless steel double-skin panel consists of a corrugated sheet sandwiched between two face sheets and a flange installed on the rim of the panel. Adoption of the laser spot welding in jointing these materials each other has realized such a welded structure with less thermal deformation. This structure has these advantages; the laser spot welding controlling the penetration depth precisely secures resistance to corrosion equivalent to the base material and good design of a luster specific to stainless steels without leaving any welding marks on the outer sheet; the flange installed on the panel raises the stiffness and strength, which enables the use of conventional methods including resistance spot welding just the way they are to joint with other materials. An equivalent stiffness model is required to apply the double-skin structure in a large structure like a rail vehicle body to study the stiffness and the vibration mode in the double-skin structure. But there is a problem that application of FEM model adopting the double-skin structure in detail to a large structure increases the load on the calculator. Thus we tried to solve this problem by creating an equivalent stiffness model of the double-skin panel. First of all, we formulated the equivalent stiffness model of the double-skin panel and studied the validity of the model based on the result of the mechanical property assessment test of a small specimen. Then we prototyped a full-scale rolling stock on which a SUS double-skin panel was installed to conduct various load tests, and evaluated the validity of the model by comparing the measurement value of the deformation amount of the vehicle structure with the calculation result of the equivalent stiffness model. As a result, the possibility of application of double-skin panels to large structures was achieved.
If the cutting speed is high, the cutting temperature will also be high and that may reduce the tool life remarkably. However, use of a cutting fluid in high-cutting speed conditions will increase the thermal shock and can cause thermal cracks in the tool, thus resulting in increased tool wear. In this study, the heat generated by oxidation during cutting was suppressed by blowing nitrogen gas onto the cutting point in order to lower the cutting temperature and thus to prolong the tool life. As result, blowing nitrogen gas during cutting operations at high speeds and high feed rates, increased the tool life about two times, which allowed higher speeds and higher feed rates, thus reducing the total cutting time required. It was found that the blowing nitrogen gas makes it possible to improve productivity in a high-speed, high-feed rate milling operation.
In optical devices, the demand of glass lenses with complicated shapes like Fresnel shape is recently growing up for the purpose of improving its heat resistance and optical performances. The study suggests a new machining process for cemented tungsten carbide mold with Fresnel shape, aiming at high precision machining. In the proposed process, the curved surfaces except for sharp edges are at first machined by the conventional grinding method with a disk type metal bonded diamond wheel. Then, sharp edges are created on curved surfaces by fly cutting method with knife edged single crystal diamond tool. Fly cutting method is expected to reduce tool wear due to the intermittent machining process. From fundamental V-microgrooving experiments of WC by fly cutting and shaping, it is clarified that the damage of cutting tool by fly cutting is reduced, compared to shaping. Therefore, complex machining of Fresnel shape by proposed machining method allows sharp edges to create to WC mold. As a result, it is found that the proposed machining method has the potential of producing a high precision glass lens mold with Fresnel shape effectively.
Chemical-mechanical polishing (CMP) has been widely accepted for the planarization of multi-layer structures in semiconductor manufacturing. Micro-scratch is the typical defect made during the CMP process, which are produced mainly because of agglomeration of slurry. Defects like micro-scratch lead to severe circuit failure, and affects yield. In this study, we described approaches to a production-worthy CMP process to prevent impact of micro-scratches on product wafer and lead to yield improvement. We have studied the effects of slurry filtration, pad cut rate of pad conditioner disks, and pad grooving design of the hard pads. By optimizing the consumables and polishing conditions, the hard pad-pad process showed 80% improvement in defectivity compared to the stack-type pad process.
In order to prepare a reliable NC program, which can avoid cutting troubles and achieve high machining productivity and accuracy, a sophisticated cutting process simulator is required to previously predict the target cutting operation. However, a conventional simulator using Z-map or B-rep model for representation of geometrical cutting shapes has the problem to treat geometrical cutting shapes which have overhang shapes or consist of successive tiny surfaces. Hence, in this study, voxel model is applied to predict the changes of geometrical cutting shape during the cutting operation. Voxel model generally expends large memory volume, therefore the octree data structure of voxels is adopted to reduce the memory consumption and improve the accuracy to represent complicated three-dimensional objects. Additionally, the developed cutting force simulator is integrated to the geometrical cutting shape simulator to predict cutting forces before the cutting operation. Cutting forces can be predicted by the cutting force simulator using cutting parameters such as depths of cut and stepover detected by the geometrical cutting shape simulator.
The performance of super abrasive wheels is influenced largely by the wheel working surface conditions such as the distribution and shape of cutting edges, the loading formation status, the depth of chip pocket and so on, which change with truing and dressing conditions, and grinding process in addition to the wheel specification. The research deals with the automatic image processing system for working surface of CBN wheel. The system is newly developed by adding two following matters to the system developed in our previous researches. The software programs of image processing for the dressed cutting edge and loading are newly built in addition to the software programs developed previously for the trued and ground cutting edge. And also the computer control equipment for deciding automatically the microscope observation position parallel to wheel spindle direction is manufactured additionally. Using the new system, the behavior of wheel surface in dressing process and grinding process is examined and, as the results, the availability of system is ascertained.
A gait analysis plays important role for detecting the medical condition of a person and applying to make rehabilitation plans for disabled people. Therefore, various systems for measuring walking behavior of a person have been constructed and many research works have been reported. The conceptual design of a newly developed gait analyzing machine is described. And the function of each subsystem of the machine is considered. Last, a method for processing for images and calculating various parameters such as step length, step width and angle between each two consequent foots, etc. is presented. In order to confirm the justice of the concept of the system, a prototyping system have been constructed, and various foot prints of people has been tested. The test gives good result.
Recently, remote education methods have been needed due to the globalization of production activity in companies. Moreover, it is becoming difficult to perform conventional on-the-job training (OJT) due to a reduction in the number of skilled domestic engineers. Therefore, we are developing a New OJT system as a remote e-learning skill education support system. The prototype of the system has now been developed. However, it is only able to provide education in low-level skills (education of skill level 1 is described later). The purpose of this research is to investigate education in high-level skills using the New OJT system, and to raise the level of the learner's skills. According to the finding of brain science, the discovery of “novelty” attracts attention. In addition, it is assumed that the selection of an action becomes adequate by correcting the incorrect answer action. Therefore, the following three methods are proposed for improving the learner's skill level. (1) Mistakes and problems are experienced as incorrect answer actions in the skill education. (2) A mental model to deal with the mistakes and problems that occur by accident. (3) A cause conception training method that is concerned with the causes and measures of the mistakes and problems. In an experiment, a learner studied the operation of the Numerical Control (NC) machine using the above-mentioned three methods. As skill level is classified into four classes, the learner's skill was evaluated on each class. Moreover, improvement in the learner's skill level was observed. Thus, the effectiveness of the proposed skill level improvement method was shown.
A lot of techniques of tool path generation for 5-axis controlled machining that consider tool interference are already proposed. However, those methods have outputted impossible tool path for machine tool, because movable range of driving axes of machine tool is not considered. Moreover, discontinuous tool path threatens to cause deterioration of surface quality. This study has been aiming to generate the tool path considering movable range of machine tool and continuity of tool attitude change. We have already proposed the original 2-dimensional configuration space that indicates possible tool attitude at each cutting point. The method proposed in this report searches the shortest tool path using 3-dimensional configuration space that corresponds to available tool attitudes with consideration of tool interference and movable range of machine tool. As a result, usefulness of the devised method was experimentally confirmed.
Generating the upper limb posture of a human arm is important when executing tasks involving position and force control. In this article, we derive the evaluation function to generate the upper limb posture of a human arm when connecting an RCA plug. We measure the upper limb posture of one subject, while connecting the plug, to determine factors in the evaluation function and of eight more subjects on different positional plugs, to estimate the factor values. Based from the experimental results, the evaluation function can be expressed as a weighted linear sum of nine factors such as power transmissibility of joints, torque, and manipulability measure of joints. It was shown that the generated upper limb posture is close enough to the measured posture. The most important constituent factors of the evaluation function are found to be manipulability measure of both elbow and wrist, and the wrist torque.
Older driver death in traffic is about 40% of all deaths and increasing sharply from year to year. The purpose of this research is to develop a system to check the driving ability of the elderly with comprehensive measurement of visual, cognitive and performance necessary for safe driving. The method and prototype-system for measuring the driving ability (especially cognitive and decision performance) of the elderly were created. In this system, field of view, static visual acuity for under low contrast and glare environment, cognitive and decision performance to three levels of difficulty (magnitude of driver workload) were measured. In sample measurements of visual performances, among the elderly, the detection rate was notably lower with driving operations (useful field of view) than without (static field of view), indicating a marked reduction in field of view when driving.
This paper describes the moving characteristics of an in-pipe mobile robot using a wheel drive mechanism for inside bent pipes. The wheel mechanism can drive the wheels and also press them against the pipe wall using only a single actuator and a planetary gear drive mechanisms. The actuator torque while moving inside a bent pipe can be given by multiplying a constant of the radius of curvature and diameter of the bent pipes by the actuator torque while moving inside a straight pipe. The results of the calculation were in agreement with the experimental value of the prototype robot, which is 45mm in diameter and 130mm length by using flexible coupling. It can move automatically and smoothly inside the piping composed of the vertical pipe, the bent pipe, and the stepped pipe.