In this study, we introduce research aimed at developing a compact particle-excitation flow control valve that enables continuous control of air flow rate. We have been developing a compact control valve with continuous flow control for application to soft actuators. The control valve that we are developing uses particles as a valve plug, which does not require a valve plug positioning function and allows the control valve to be miniaturized. Furthermore, by controlling the movements of the particles on the orifice, the control flow rate can be made finer and the response can be improved. On the other hand, the past driving principle used the resonant mode of an oscillator utilizing a piezoelectric element (PZT) to control the motion of the particles. In this vibration mode, the size of the oscillator limits the miniaturization. Therefore, we propose a drive method that uses simple plate deflection vibration mode. This drive method eliminates the need for a large oscillator, and thus reduces the size of the control valve. To confirm the feasibility of the proposed drive method, we fabricated a prototype and evaluated its characteristics during flow control.

This paper describes the development of a three-dimensional (3D) indentation test system capable of observing the distribution of mechanical properties in structural materials. Serial sectioning with destructive treatment has traditionally been used as a method for observing microstructure within materials in three dimensions. The serial sectioning methods using precision cutting has attracted particular attention as it enables the observation of large sample volumes. However, those methods can only observe the microstructure as image, not the mechanical properties such as hardness and elastic modulus. To measure the 3D distribution of the mechanical properties of the material, it is effective to combine repeated cutting and indentation tests on each cutting surface. Morever, combining the image observation and mechanical property tests could allow a more sophisticated analysis of the interior of material. To implement this method, we have constructed an indentation test system on a precision machine using a Berkovich indenter, micro-force sensor, and micro-movement stage.In order to achieve a 3D indentation test, it is considered necessary to unify the measurement positions in the depth direction. Furthermore, the unloading rate needs to be controlled in order to carry out stable indentation tests. Therefore, we propose a method of 3D indentation test that can precisely control the maximum depth of indentation and unloading speed.In this paper, we devise a method for driving the constructed system and a method for obtaining data and confirm the accuracy of these methods by experiment. In addition, we determine indentation depth and unloading speed which are suitable for our method by performing indentation tests on a block for ultra-microhardness. Finally, we practice 3D indentation test in which the cutting and indentation tests are repeated on specimens with different mechanical properties in the depth direction. Experimental results show that our indentation test system is appropriate to measure three-dimensional mechanical properties inside the material.

This paper proposes a drive principle that aims to improve the control characteristics of a particle-excitation flow control valve capable of continuous air flow control. Aiming at application to a small servo valve, the authors have developed a particle-excitation flow control valve that controls flow rate by separating particles, which act as a valve element, from an orifice that is opened by the oscillation of a piezoelectric element. This paper proposes a method of more finely adjusting the motion of the particles. This method makes it possible to adjust to what degree each orifice opens, thereby refining the control of the flow rate and improving the responsiveness of the valve. Here, the authors produce a prototype, evaluate its characteristics, and confirm its effectiveness.

From the viewpoint of disaster prevention, it is expected the unmanned automation of daily inspection/health monitoring and diagnostic work for facilities/structures in places where it is difficult to let the inspectors going such as offshore plant and dangerous places. By adopting remote controlled/autonomous robot, regarding the occurrence of abnormality due to human factors, breakage of facilities due to aging of facilities, malfunction caused by them, accidents by increasing the frequency of periodic inspection, it becomes possible to prevent it in advance. In addition, introduction of the robot makes it possible to conduct inspection work even during operation, so it is expected that the availability factor of facilities in such environment will be improved. This paper described about the plant disaster prevention challenge of the World Robot Summit 2020 disaster robotics category held at the Fukushima Robot Test Field in October 2021. The competition concept and the competition rule were introduced. The analysis of the competition results were shown and considered based on competition results. Finally, the lessons learned was mentioned.

The pneumatic actuators have sufficient potential to build assembly work systems aimed at lowering costs. However, the required control valve which is capable of continuous flow rate control has the problem that it is difficult to reduce the size and weight. Therefore, the authors are developing a Particle Excitation Flow Control Valve that is expected to be smaller and lighter. In this paper, we propose a new vibration mode to reduce the size of the control valve. We investigated the effect of the applied pneumatic pressure on the new mode and whether it is actually possible to drive in that mode.

The authors are developing a Particle Excitation Flow Control Valve development, at aiming at application to a small servo valve. For efficiency, mechanism conditions using vibration in the perpendicular to the air pressure was proposed. In this report, the driving was proposed that can generate vibration acceleration at an arbitrary angle with respect to air pressure and evaluated its effectiveness by conducting experiments.

This paper reports a novel driving method for particle-excitation flow control valve. The valve that we have designed in previous reports can control air flow continuously with small size and light weight. Because the valve conditions air flow, using particle excitation by piezo vibration, the valve has potential for high response. However, in previous model, the vibration direction is opposite to air flow direction and a large scale vibration is necessary to open the valve. In this report, to decrease necessary vibration scale, we design novel driving mechanism using torsional vibration. The method generates vibration that is perpendicular to air flow by torsional vibration. First, we explain the designed mechanism and calculate the vibration scale to open the valve. And we design a prototype that can generate torsional vibration to check the mechanism. Additionally, we measure the vibration scale at valve opening condition in experiment and compare calculated and experimental results. Through this study, we show the advantage of the mechanism.

In general, it is known that when cutting an iron-based material with a diamond tool, carbon in the tool thermally diffuses into the work piece, causing significant tool wear. In this research, we aim at modeling the wear phenomenon during diamond cutting to pure iron based on theoretical diffusion at the time of simple contact between iron carbons. In this report, we consider differences between tool wear and initial theory in cutting.

Tools used in diamond turning of steels undergo severe tool wear. In this study, several steels were heat-treated and nitrided to investigate the wear mitigating effect of the microstructure of nitrided steels. The results indicate that the tool wear is mitigated with increase in the chromium content of steel. The results also indicate that chromium carbides are transformed into chromium nitrides by nitriding. Thermodynamic analyses demonstrated that chromium nitrides are stable when in contact with diamond at the cutting temperature. Further, the ratio of iron nitrides to iron increased because the iron levels decreased as the chromium levels increased. Although diamond reacts with iron nitrides, the interaction is considerably weaker than that with iron.

We have developed an automated three-dimensional information acquisition system based on consecutive precision cutting and cross-sectional image recording. In previous report, micro Vickers indentation tests were conducted at regular intervals in image recording process and the micro hardness distribution measurements of steels were performed in high-precision consecutive cutting and observation. However, the interval was 70 μm because indentation depth was almost 5 μm. In this study, on-machine measurement of micro hardness less than depth of 1 μm was examined using a micro force sensor, a piezo stage, and a Berkovich indenter.

In planarization processes of sapphire, lapping process takes a long time because sapphire is a hard material. In contrast, superfinishing, which involves fixed abrasive machining, can substitute for lapping, and it would be possible to shorten the amount of processing time. In this work, vitrified-bonded diamond superabrasive stones with different grain diameters are developed. Then, multistage superfinishing is investigated by combining these stones. Results indicate that the multistage process is capable of producing a 2 nmRa surface, equivalent of a lapped surface in less than 10 min. To improve the process of multistage superfinishing, a removal amount estimation method is developed based on the real contact pressure calculation. The working area ratio of the stone was calculated by considering elastic deformation during superfinishing. The contact ratio of sapphire is calculated considering the roughness of the pre-finished surface and grain depth of cut. Accordingly, the real contact pressure is calculated to estimate the removal amount during superfinishing and finished surface roughness was expected.

Diamond tools wear extremely in single point turning of steels. It is thought that carbon atoms in diamond diffuse into iron. Characteristics of steels can be widely changed by heat treatment and surface modification. In our past work, we have focused on heat treatment and have changed the microstructure to suppress the tool wear. We have found carbides precipitated in α-phase suppress the tool wear. Then, we have studied on carburized steels. Tool wear was examined in comparison with element concentration, hardness, and carbide area ratio of carburized steels. Accordingly, large-size and high-circularity carbides precipitated on grain boundaries were related to increase the tool wear. However, it was not clear which factors may suppress the tool wear. In this study, past experimental data was used to examine relation between tool wear and microstructure of carburized steels. We used 21 sets of data, which contains element concentration, hardness, and carbide area ratio of carburized JIS SKD61 steels. Based on it, a decision tree which explains tool wear was made by using C4.5 classification algorithm. The decision tree revealed carburized steels without carbides whose area is ranging from 1 to 3 μm2 and whose circularity is less than 0.5 tend to increase the tool wear. On the other hand, carburized steels with above-mentioned carbides, and with carbides whose area is ranging from 0.07 to 1 μm2 and whose circularity is less than 0.5 suppress tool wear the best. Those results suggest that the decision tree can be used to predict microstructure which may suppress tool wear effectively.

In general, high controllability and high response devices for pneumatic actuator are demanded. We have designed the flow control valve that can control flow rate smoothly. This flow control valve has simple structure using PZT resonance mode. However, this control valve has problem of flow rate stability. In this paper, we aimed at stability of flow rate, and focused on orifice condition of the valve. We designed new prototypes improving orifice condition and measured flow characteristics using prototype. From the results, we verified the condition to steady flow rate of the valve.

This paper reports an improvement of the particle-excitation flow control valve. The valve that we have designed in previous reports can control air flow, using particle excitation by piezoelectric resonance, and has the following advantages: small size, lightweight, high response and continuous airflow control. However, in our previous models, the relationship between the driving voltage and the flow quantity was nonlinear. In this report, we improved the valve to realize proportional flow control. The valve consists of the orifice plate, that has some orifices, and steel particles to seal the orifices and piezoelectric transducer. It controls air flow by the voltage applied to the transducer. For proportional flow control, it is important to adjust the orifice position adequately. In this report, we optimized the orifice position, considering resonance condition of the valve. We designed the experimental prototype using a bolt-clamped Langevin type transducer and decided orifice position. And we evaluated its vibration properties and flow-rate characteristics. The experimental results showed that our designed prototype can proportionally control airflow.

Diamond cutting tools show severe wear in turning of steels. In previous paper, it was shown that carbides on ferrite phase, which were precipitated by carburization, suppressed the diamond tool wear. In this paper, detailed distribution of constituents of the carbides was analyzed by EDS (energy-dispersive X-ray spectroscopy). In addition, characteristics of each carbide such as occupancy, diameter, and degree of circularity were measured. Results indicate that those characteristics of the carbides influence suppression of the tool wear.